New Clues Could Solve Case of the Dutch Girl Lost in Africa

Uganda’s Murchison Falls National Park is home to a lot of dangerous wildlife. The rivers teem with crocodiles and tusked hippos. Lions and leopards stalk by night. There are elephants that can crush anything in their path and massive cape buffalos with razor-sharp horns more than three feet across.

When 21-year-old Dutch medical student Sophia Koetsier disappeared here under mysterious circumstances in the fall of 2015, authorities tried to blame it on an animal attack, according to Dutch media reports.

Eight years later, however, a potential new lead has surfaced, and the new director of the Criminal Investigations Directorate (CID) in Uganda has reopened the investigation into Sophia’s mysterious disappearance. Instead of a croc or a big cat, it now appears that Sophia may have fallen prey to the most dangerous species of all: man.

Sophia’s mother, Marije Slijkerman, always wondered about the possibility of human involvement based on the evidence recovered in the case.

“I had a strong sense that things were not right,” Slijkerman told The Daily Beast in an exclusive interview. “That feeling has remained, to this day, very strongly.”

Slijkerman has spent the better part of a decade relentlessly searching for answers. And at long last she may have uncovered a clue hinting at another party’s potential role in her daughter’s disappearance, after tracking down a key witness earlier this year. New and explosive DNA evidence pointing to another party’s involvement has also emerged, thanks to Slijkerman’s indefatigable efforts. The Daily Beast has exclusive access to the DNA report, as well as investigation files, photographic records, key witnesses, and timeline.

“I will continue fighting, no matter how hard and difficult it is,” Slijkerman said. “I will keep doing whatever I can to find out where she is and what happened to her.”

In conversation Slijkerman comes across as articulate and precise. Her gaze is steely and intense, and one senses that she does not suffer fools lightly. It seems clear that this woman would be a very formidable enemy. You can’t envy any Ugandan bureaucrat or official who crosses her, let alone someone who may have harmed her daughter.

‘Strange and Unreal’ Trail of Clues

Sophia Koetsier was last observed near a small cluster of cabins and outbuildings that functions as a student center for the Uganda Wildlife Authority [UWA], according to the Ugandan police report. The center is located in a wooded area on a dirt road about a third of a mile from a branch of the Nile River that flows into Lake Albert. She had been touring the river and the famous waterfall for which the park is named with two other students, and they had stopped off at the UWA center to spend the night.

A UWA worker spotted Koetsier near the camp’s latrine hut around 6:30 p.m. on Oct. 28, just as it was beginning to grow dark. She was “holding an empty Rwenzori mineral water bottle in her hands” which she had been using to collect trash, the police report states. And she was looking in the direction of the river, according to the witness. Koetsier would never be seen again.

After the other students noticed she was missing, a small search party ventured half-way to the river and returned at about 8 p.m. No further search was conducted that night on account of the darkness.

The search resumed the next morning. At around 9 a.m., a party of rangers and soldiers found a single clue near the river bank: Koetsier’s water bottle. Nothing else was found that day.

However, the next morning at around 11 a.m. rescue workers discovered more of Koetsier’s clothing and personal effects. The items found included a small souvenir purse she’d bought in Kampala, which was completely empty. One boot, but only the sole from the other boot. A pair of sunglasses and a half-torn 1,000-shilling banknote. They were strewn along a 50-yard stretch on the north bank of the Nile, about 600 yards—or less than a 15-minute walk—from where she was last seen. The new items were only five to six yards from where the water bottle had been discovered the day before—yet somehow searchers had not seen them at that time.

This discrepancy seemed like a red flag to Slijkerman, especially since pieces of Koetsier’s clothing had been bound to or draped over branches and should have been easy to spot by trained rescue workers. Also peculiar was the location of her panties, which were found high in a riverside tree. Marije began to wonder if the items might have been placed there by someone, possibly after the initial search that turned up the water bottle.

“When seeing this very puzzling trail of items I did not see Sophia’s hand there,” Slijkerman said. “The items were definitely produced and laid out by human hands. It felt very strange and unreal.”

‘Brilliant and Hard-Working Student’

Before things took a dark turn, Koetsier had been traveling with two other Dutch medical students on what was supposed to be a safari adventure to conclude their internship at the Lubaga (then Rubaga) Hospital in Kampala, Uganda’s capital city. All three women had spent the last eight weeks assisting with routine surgeries, delivering babies, and soaking up the local culture.

By all accounts Koetsier adjusted easily to life in Uganda, and quickly became a favorite with the hospital staff—in no small part due to her charismatic, engaging personality.

Slijkerman characterizes her daughter as “an extrovert” and “social, curious, talks to everyone. She knows what she wants and what she doesn’t want.”

A woman of many talents, Koetsier speaks fluent English and is an accomplished pianist. “She is a fast learner, with multiple talents,” her mother said.

That description of her talents also matches reports from Koetsier’s co-workers in Uganda.

Christine Moru, one of the midwives at the Lubaga hospital, describes Koetsier as “a brilliant and hard-working student, courageous and very focused on learning. She picks things up very quickly, I only had to show her something once and she could do it.”

Christine Achen, another Ugandan friend who came to know Koetsier during her stay, said: “The Sophia we know is jolly, bubbly, fun, full of excitement, [and] loves to dance. [She] never complains, never falls sick.”

“She came to the hospital every day on time and she was always cheerful,” Moru said.

At the time she went missing, Koetsier was also at least somewhat familiar with the country, having made several other excursions in Uganda over the course of her internship.

Considering Staying in Africa

Koetsier wrote regular emails home to her family during her tenure at the hospital. These letters provide powerful insights into her personality, as well as her social life and living conditions in the weeks before she went missing.

“The house where we are staying is fairly big but there is hardly any furniture. In the living room only a couch and a small desk. In essence we sit on the floor,” Koetsier wrote in one of her first letters home from Uganda.

The portrait that emerges from these missives is of a gifted, even brilliant, young woman, passionate about her work, and enthralled by her African adventures.

“On our first day we immediately made friends with the local children,” she wrote on Sept. 1, 2015. “[The children] wave and laugh at us. They say, ‘Hi mzungu.’ ‘Mzungu’ means white person, in a neutral way. The children love it when you say something back to them.”

Koetsier also exhibits an intense curiosity about Ugandan culture, including attempting to learn the local dialect—and even taking it in stride when she’s made the butt of a good joke:

“This evening I asked [the] guys in the house if they could teach me some Luganda. One of them taught me ‘olinga toya’ which means ‘I am funny,’ according to him. I liked having learned this. Then he wrote it on my arm and a bit later I found out that it meant: ‘I am a toilet.”’

According to her letters, she was soon given the Lugandan nickname “Najigobe” which means “morning sunshine.”

She also comes across as a dedicated physician-in-training.

Midwife Moru told The Daily Beast that Koetsier “seemed a born doctor to me. Always eager to help, wherever and however she could. She’d be mopping floors, if needed. I have never seen a mzungu do that. She learned from us but we learned from her too.”

Djoeke Rondagh, a close friend of Koetsier’s from Holland, was also in regular communication with Koetsier during her stay in Uganda. In an interview with The Daily Beast, Rondagh described Koetsier as having “a lot of humor” and “always up for a party.”

“She is always happy and very social, interested in everybody around her,” said Rondagh, who like Koetsier studied medicine and is now a third-year student in psychiatry in the Netherlands. Rondagh also said that Koetsier was committed to her future in medicine.

“She found her studies very important and worked hard for them,” Rondagh said.

Her strong work ethic also shines through in her letters home, as Koetsier repeatedly shows genuine interest in her patients and true passion for science.

And her personal life seems to have been positive and healthy. For instance, on Sept. 30 she wrote:

“I get along very well with everyone in the house. Every night is a bit of a party because we are with so many. We watch movies, play music and dance a bit, or we play cards. We do ball games in the garden, or a work out with beach balls. You can also play squash against yourself by using the bare wall in the living room.”

In fact, Sophia seems completely smitten with her new surroundings, even writing in a letter home that she was “considering simply staying in Africa” because she had fallen in love with “the way of life and the habits.”

The good times seem to have lasted all the way to the end of the internship, and her last letter home indicates she was in high spirits and thinking about the future.

“After saying goodbye to everyone in the maternity ward we also stopped by the other wards. I sincerely regret my stay here is over. All the people in the hospital are so sweet. I will really miss them and hope to be back one day. Who knows, as a doctor of tropical medicine?”

And so in late October, with the internship behind them, Koetsier and her two fellow students set out for what should have been a final excursion before heading back to Europe.

Missing Persons Cases Shouldn’t Have a Crime Scene

Despite the authorities’ initial claims, the circumstances surrounding Koetsier’s disappearance convinced many observers that assault by an animal was unlikely. For example, photographs taken at the scene show Koetsier’s pants had been ripped into small strips and some of the strips had been laid out in clear sight on foliage and logs. Additional strips were found tied to fallen tree limbs on the shore.

And then there were her panties, which had been slipped over a branch about 16 feet high in a tree growing on the bank—a place that would have been extremely difficult to reach in darkness on the night she disappeared.

There was no blood on any of the recovered items, leading park rangers involved in the search to deny the hypothesis that an animal was responsible.

Asked whether there was any evidence that this could have been the result of an animal attack, Murchison Falls ranger Henry Buzu, who helped look for Koetsier, told the Dutch TV program Break Free: “There’s none. No.”

Buzu added: “If she had been eaten up by the animals, animals eat on the land, we would have been able to see the activity. Some parts would have remained.”

Buzu also told interviewers that a newcomer to the student center would have a tough time finding the river on her own, especially in low-light conditions.

“It is very difficult for someone who has come here for the first time to find the actual path to the river,” Buzu said.

In addition to the animal-attack theory, officials at the time also speculated that Koetsier had either suffered some kind of mysterious accident or had purposely taken her own life, and the case went stale.

But Slijkerman never really bought into any of those theories.

She believes it can’t be ruled out that the clothes and belongings might have been deliberately placed along the river to cover up or disguise a crime against her daughter. The fact that the water bottle was found first, and nothing else at all was recovered that same day, also aroused her suspicion.

That’s because the bottle was recovered just a few yards from where the other articles were found just 26 hours later—leading Slijkerman to consider the possibility that the other articles may have been planted after the fact.

When she asked one of the cops why the water bottle and the other items were not found on the same day, despite the respective recovery points being so close together, she got what seemed like a dubious response.

“According to the policeman it had been raining the night Sophia disappeared and all [the other] items had been under water, due to rising river level.”

The bottle, the cop said, was found slightly higher up on shore.

“That explanation makes no sense at all, as some items were not found on the ground but higher,” including up in a tree. “When you look at the photographs of the items, and the tall grass surrounding the spot, it is clear that it had not been immersed in water. Also, the river cannot rise half a meter or more in one night, and then go down the same amount one day later,” Slijkerman said.

The thought began to take hold that a person or persons might have doctored the evidence. And Slijkerman isn’t the only one who is concerned about the possible cover-up of a crime: “We have been in touch with a few Dutch policemen, who immediately said that [in their personal opinion] this looked like a manipulated or staged scene,” she said.

A retired Dutch law enforcement officer with close knowledge of the case told The Daily Beast that he too surmised that the evidence might have been manipulated. The former homicide detective agreed to speak only on the condition of anonymity, he said this was one of the oddest cases he had ever encountered.

“Most missing persons cases do not have a ‘crime scene.’ How did Sophia’s knickers end up some 5 meters high up in a tree? How was the water bottle found, but not her other belongings that were nearby, only to be found a day later? How could the shoe that was found be so clean? How did the strips of fabric from Sophia’s pants end up there? Where are the rest of those pants? Where are Sophia’s other clothes? This crime scene raises so many questions,” the former detective said.

Of those many questions, he said the foremost might be whether “the other items were actually there at the same time [the water bottle was found], or if they were placed there later?” he said. “Based on what I have seen, the crime scene could be staged.”

The DNA Evidence

The indications of foul play are not limited only to the opinions of experts and Koetsier’s family. The science also seems to back these claims.

The Dutch government never conducted a full DNA analysis of the recovered personal effects, beyond what was needed to establish Koetsier’s identity. As part of their renewed investigation, Ugandan authorities recently claimed they were going to run their own DNA tests. But no report has yet been shared with the family or made public.

But we do have the lab report from a comprehensive DNA analysis that Slijkerman commissioned and paid for out of her own pocket. And the findings are troubling.

The report was prepared by Independent Forensic Services (IFS), a private laboratory based in the U.S. The chief author and lead scientist was a man named Richard Eikelenboom, a former researcher with the Dutch government’s Netherlands Forensic Institute (IFS).

Eikelenboom and his team subjected every piece of evidence—including each individual piece of recovered fabric—to rigorous tests. They then cross-referenced their findings to the profiles of each of the 28 people who could have inadvertently left behind a sample of their own DNA. These included members of the search parties, such as Ranger Buzu, as well as Ugandan police officers involved in the investigation, and Koetsier’s own parents.

The ISF team ultimately discovered the presence of male DNA that could not be accounted for.

“In total 6 alleles have been obtained in the Y-chromosomal DNA-investigation which have not been found in the DNA-profiles of those involved in the investigation.”

And it wasn’t just a single piece of evidence that bore the telltale traces.

“The majority of these alleles are found at least twice on various pieces of evidence. As a result the evidential value of these alleles is increased. Based on these DNA results there is very strong support for the hypothesis that at least one unknown male, but likely more, have left DNA on the various pieces of evidence,” the IFS team wrote, adding that:

“[T]he question arises what part the (as of yet) unknown male(s), whose DNA cannot be identified, have played in the disappearance of Sophia.”

The sheer volume of DNA from the unknown man or men led the team to conclude that their findings invalidated the Ugandan government’s hypotheses of suicide, accident, or animal attack.

“There is no logical explanation for the fact that an unknown male(s) contributes DNA to torn pieces of fabric, knickers, the right shoe and the insoles all belonging to Sophia Koetsier,” the IFS team wrote.

‘Someone with Knowledge of the Area’

To better understand how or why the evidence in Koetsier’s case might have been planted, and who might have done so, we reached out to Dr. Claire Ferguson of Australia’s Queensland University of Technology. Ferguson is one of the world’s foremost experts in the field of staged homicide—that is, murders which are made to look like a suicide or an accident so as to cover up the crime.

In such cases, “it is not uncommon for evidence to be manipulated in a way that is ambiguous in terms of manner of death, and the offender(s) then leave it open to investigators to determine whether they think the evidence shows suicide or accident,” Ferguson said.

“There are numerous examples of this where the body of the person is never discovered or not discovered for a very long time, most often because it is concealed by the offender (buried, burned, hidden, etc).”

Ferguson explained that perpetrators returning to crime scenes and manipulating evidence after the fact is “not uncommon” in staged homicide cases, and is often used to construct a “false scenario” so as to mislead authorities.

So what kind of suspect could have had the wherewithal to successfully navigate the area and place evidence in such a way as to fool the Ugandan authorities?

Criminology professor Ferguson has constructed a profile that is also in keeping with Ranger Buzu’s testimony that a person unfamiliar with the area would have had trouble even finding the river in the dark. Ferguson believes the culprit was someone familiar with the student center and its surroundings.

“What I would infer, is that this offender or offenders were comfortable enough in the area to deposit evidence while it was a known crime scene and when it was subject to much more monitoring than normal,” she said. “This would require some knowledge of the area and investigation.”

A ‘Chaotic’ and ‘Disorganized’ Search

The cops did not spend time looking for suspects who might match such a description.

According to Slijkerman, it seems the police work was less than thorough.

Koetsier’s mother had come to Uganda that fall to visit her daughter near the end of her internship. Slijkerman had never planned to join the safari and was still in the city when she received word of her daughter’s disappearance. Less than 36 hours later, she was at the park. She was then driven to the UWA student center in the company of Koetsier’s two fellow interns.

Slijkerman arrived to find a troubling scene.

“The situation on the ground seemed chaotic, not very organized and it was not clear what was being done,” she said.

“A list of all those present at that accommodation was not made, for example, which should be the first thing you do.”

Not content to rely on the cops, Slijkerman began seeking information from Koetsier’s two traveling companions, as well as their driver. To protect their identities we’ll refer to the companions as Sandra van Dalen and Nina Smeets, and the driver as David Atubo.

Slijkerman already knew that the trip had not been going well, as Smeets had telephoned her around the same time Koetsier went missing to say they were worried about Koetsier and thinking of cutting their travels short.

It is not entirely clear what happened in the short time span between their arrival at their accommodations at the student center and Koetsier’s disappearance, Slijkerman said.

In the statement given to Uganda police, Van Dalen accused Koetsier of failing to watch over their luggage while the other two women went to the latrine. Upon coming back from the toilet, she said they had argued about this. In another version of the story, later given to Dutch police, the luggage argument was omitted.

Slijkerman also said there were inconsistencies in the driver’s story:

“[Atubo’s] position at the time is not clear. He says he noticed Sophia was not in the toilet as all three doors were open, but from the spot he claims to have been sitting, the toilet is blocked by shrubbery.”

(Atubo declined to be interviewed for this article. Neither Smeets nor Van Dalen had responded to interview requests at the time of publication.)

Authorities soon ruled out the other two med students and the driver as suspects. While there had been some tension within the party in the days leading up to Koetsier’s disappearance, there is no evidence her safari companions were involved in what befell her, and their alibis for the night in question and ensuing days were verified by multiple witnesses.

Meanwhile, back at the student center, Slijkerman claims the local cops continued to bungle the investigation.

“I later heard they cordoned off the area [on the fourth day of the search], disregarding the fact that many people, including myself, had been walking around there over the past days, destroying evidence and making new traces and tracks,” Slijkerman said.

According to her, police took handwritten statements from some of those present but did not conduct rigorous questioning of any witnesses. Even the use of search dogs appears to have been mishandled.

“Dogs were active on the scene of crime that morning as well, despite not having been offered anything with Sophia’s scent,” said Slijkerman, who has made dozens of trips to Uganda since 2015 in search of the truth.

‘You Expect Your Country to Help’

The mistakes by Ugandan law enforcement weren’t limited to their efforts in the field. More than a month after Koetsier’s belongings were recovered, they had still not been transferred to Kampala for analysis, forcing an agent from the Dutch embassy to travel to the region to retrieve them.

Those vital pieces of evidence were “handed to [the agent] in a brown paper bag,” Slijkerman said.

According to Slijkerman, one high-ranking Ugandan official even admitted to her that the investigation had been mishandled, saying: “It is clear to me this case has not been taken seriously and has been kept at a local level far too long.”

Unfortunately, authorities in the Netherlands also failed to provide much-needed assistance in the search for Koetsier. The Dutch homicide detective told The Daily Beast that, unlike the FBI in the U.S., his national police prefer to allow their local counterparts to investigate cases involving Dutch citizens in other countries.

The retired officer was critical of this practice, especially in Koetsier’s case, saying it was “sad to see that a mother has to do so much to find her missing daughter and to get answers about what happened. It should not be the case that families of persons who go missing have to bear such a burden on top of everything else they are going through.”

As we’ve seen, Dutch officials refused even to do DNA testing on the recovered items, forcing Slijkerman to pay for IFS’s services.

“When you’re a citizen of one of the richest and most developed countries in the world, you somehow expect your country will assist and help you when something terrible happens to you, such as your child going missing in a far away country on another continent,” said Slijkerman, who has a background in journalism and film.

“We have discovered you can only believe this as long as nothing terrible does happen to you. This was a huge deception to us. We did not feel taken seriously by the Dutch police and public prosecutor.”

‘More Here Than Meets the Eye’

The search for Koetsier went on for almost two full weeks. One aerial drone, a helicopter, and boats were all deployed, but no other evidence as to her whereabouts came to light.

Slijkerman stayed on in the park well into November, because, “I [didn’t] know how to leave here without Sophia.”

With no suspect or additional findings, authorities at the time then chose to rule her disappearance an accident.

But Marije still believes otherwise. She still has “the strong sense that there is more here than meets the eye,” she said.

After being largely abandoned by law enforcement in her native Holland, as well as ignored by Ugandan authorities, she launched a personal mission to uncover the truth—and perhaps even to find her daughter still alive.

“When people offer their condolences, speaking about Sophia in the past tense, it feels as if they put a dagger in my chest. I always wonder: ‘What do you know that we don’t?’ Or people asking how long you intend to continue your search. We are lucky to have close friends who do not ask such questions, who understand that I cannot stop with this search for my daughter.”

And so Slijkerman continued to return to Uganda. Year after year. Asking questions. Lobbying authorities. Tracking down witnesses. And, like some relentless sleuth in a detective novel, little by little she began to uncover new clues.

In her conversations with rangers and park officials, Slijkerman stumbled upon some extraordinary evidence that Ugandan authorities had not disclosed. Namely, that the student center where Koetsier was last seen had not been a lonely outpost at the time she went missing.

Slijkerman found that there were several UWA trainers and an unknown number of soldiers from the Ugandan People’s Defense Force (UPDF) staying there at the time as part of a UWA training program. But that wasn’t all.

“Much later we learned that a six-month training [class] was actually given to some 400 UWA recruits, who were staying in a camp around two kilometers (about 1.25 miles) north of the center.”

So instead of Koetsier’s party being isolated in the bush and thus vulnerable to attack from wild animals, “there were a great deal of men in the direct area,” Slijkerman said. And, for the most part, their statements had not been taken for alibis, nor their whereabouts established at the time of Koetsier’s disappearance.

Unfortunately, violence against women and femicide is a growing problem in Uganda, as per a recent report by the UN. Human trafficking is also on the rise in the country, with cases almost doubling between 2020 and 2021 (the last year for which data is available), according to the U.S. State Department.

Police Take a ‘Second Look’

Marije thought she had a breakthrough in 2020 when Ugandan president Yoweri Museveni agreed to meet with her and subsequently ordered another investigation into the case, only to see it stall out again because of the COVID pandemic.

But two years later, in 2022, the outgoing head of the CID spoke about Koetsier on television, mentioning her as one of the most high-profile, unsolved cases in recent history in Uganda.

The incoming CID director, Tom Magambo, then decided to re-open the investigation. In September of last year, Magambo told Uganda’s national newspaper New Vision that he had appointed a special task force and even called in experts from the U.K. and Israel to take a “second look” into the case.

“I set up an interagency team that has been working for the last four months,” the director said. “They are finalizing their report.”

Part of that report is supposed to include newly taken depositions from those present in the park when Koetsier vanished (something that was not done at the time). In light of the IFS’s report, Magambo also ordered his own DNA analysis of the evidence.

So far, however, Magambo and his team are keeping their findings under wraps, and refusing to share specific details of their investigation with Slijkerman or the press. (The Ugandan authorities also did not respond to our interview request before publication.)

Slijkerman, undaunted, has made more trips to Uganda, including two this year, most recently in June. And at last she may have succeeded in getting the breakthrough she’s been chasing all these years.

For at long last, both a crucial witness and a compelling new lead have emerged. Two factors which might finally force the authorities to recant their original theory that there was no human involvement in Sophia’s disappearance.

‘Blaming the Victim’

Given the CID’s recent decision to re-open the case and the lack of evidence for the accident theory, it might seem hard to understand why the Ugandan police were initially so swift to rule out foul play.

The authorities seemed to believe that Koetsier might have taken her own life by drowning herself in the Nile due to a general misunderstanding of a medical condition that had been identified several years before she came to Uganda.

Specifically, Koetsier had been diagnosed with a bipolar condition. She had revealed this to Van Dalen and Smeets, her traveling companions, early on during the ill-fated trip to Murchison Falls. The two women in turn informed Ugandan authorities of the diagnosis after Koetsier went missing, apparently leading them to the convenient conclusion that whatever happened was her own fault.

Slijkerman believes the knowledge that Koetsier had been diagnosed as bipolar gave officials a handy excuse to curtail their investigation, essentially “blaming the victim,” as one Dutch newspaper put it.

What officials overlooked was the fact that Koetsier has a very specific form of the bipolar condition, which involves only an upswing in mental energy and activity, but without any corresponding downturn into malaise, lethargy, or negative thinking. Cutting-edge researchers in the field refer to this particular variety of the diagnosis as “unipolar mania.”

“Sophia is part of the small group with this diagnosis who only has manic episodes. We have never seen her depressed,” Slijkerman said. She also described these manic episodes as “rare” and said Koetsier always recovers rapidly and never fell behind in her studies.

Childhood friend and psychiatry student Rondagh agreed that Koetsier would never have been inclined to take her own life.

“[Sophia] was never depressed and never suicidal, she enjoys life very much,” Rondagh said.

To gain a better understanding of unipolar mania, we reached out to Dr. Martin Preisig of Switzerland’s Center for Psychiatric Epidemiology at Lausanne University Hospital, who recently co-authored a paper studying unipolar mania in several countries across the world.

Individuals in a manic phase frequently display “persistently goal-directed behavior or energy,” Preisig said. He also said that suicide rates are lower in patients with unipolar mania when compared to those suffering from the more common bipolar variety, and it “is very rare” that a person in the midst of a manic episode would deliberately seek to end their own life.

Based on expert analysis it thus seems improbable Koetsier intentionally harmed herself. But that doesn’t mean her medical condition didn’t play a role in the events leading up to her disappearance.

It does appear as though Koetsier might have been caught in a manic phase during the trip. And that this created tension within the group—tension which would have long-running implications no one could foresee at the time.

“It seems quite clear Sophia was developing a manic episode when she disappeared,” Slijkerman said. She believes that, at least in part, the episode could have been brought about by Koetsier not getting enough rest for the previous several weeks due to her workload at the hospital and subsequent travel itinerary. Stress and fatigue had caused the onset of manic phases in the past, Slijkerman said.

“As Sophia said when I last saw her: ‘You know, it’s fun, living in a student house, but it’s never quiet.’”

Potentially adding to the lack of rest was the anti-malaria drug called Malarone, which Koetsier had been taking throughout her eight-week stay in Uganda, and which can cause trouble sleeping and other side effects.

During a manic episode, Slijkerman said Koetsier “needs space and would feel held back by people who tell her to rest and such. She then seeks the company of people who barely know her, or not at all. These people don’t know what’s happening with her and will perceive her as very outgoing, bursting with energy and lots of fun.”

Koetsier’s friend Rondagh agreed with that assessment. “In a manic episode Sophia wanted to have contact with new people and sometimes avoided contact with people she knew well. I think because she knew that we would worry about her.”

Slijkerman said it was possible that, after tense moments with her friends, “Sophia got fed up with the situation, walked off, made contact with people there, and wound up somewhere else. A situation that could have started as voluntary and turned involuntary at some point.”

High Spirits

The first hint that Koetsier was slipping into a manic phase came just three days into the trip, on Oct. 26. On that day, Koetsier, Van Dalen, Smeets, and their friend and driver Atubo, were all staying in Kidepo National Park, about 95 miles northeast of Murchison Falls. The party went on a game drive that evening through the rugged savannah grasslands, taking photos of grazing wildlife like giraffes, and eland and waterbuck antelopes.

That night, as they settled in around the campfire, Koetsier was “in high spirits” and “very outgoing and social with everyone but not problematic,” according to what the local game warden later told Slijkerman.

Smeets and Van Dalen went to their respective bandas, or cabins, around 10:30 p.m. Koetsier stayed by the fire eating and drinking with Atubo and a couple of UWA interns. Atubo left around midnight to return to the hut he shared with Smeets. About an hour later, the interns accompanied Koetsier to her own hut, where Van Dalen was already asleep.

Between four and five o’clock in the morning, the warden and his assistant were awakened by a strange noise. When they investigated, they found Sophia atop the wildlife surveillance platform where she had apparently been clicking some sticks together. When they asked her to quiet down she did so immediately, according to the warden.

The warden also told Koetsier’s mother that the next morning he noticed some plastic chairs near the campfire that had been partly burned, allegedly by Koetsier herself. However whether or not the chairs were burnt intentionally or had simply been too close to the fire remains unknown.

Van Dalen woke up the next morning at 6 a.m. when the alarm on Koetsier’s phone went off. The door was locked, the window was open, and Koetsier was not in the room. When Atubo went to search for he found her near the camp kitchen. Apparently she had slept little or not at all during the night.

Psychiatrist Preisig said that Koetsier suddenly turning into a night owl is not unusual for someone in a manic phase. He cites “inflated self-esteem,” a “decreased need for sleep” and being “more talkative than usual” or experiencing a “pressure to keep talking” as additional common symptoms.

Rondagh, who has witnessed Koetsier under similar circumstances, said that during these episodes “she was very euphoric, active, interested in other people, sleeping short [hours], and did not feel tired.”

After the warden told the group about Koetsier’s late-night activities, Van Dalen and Smeets expressed their concern to her and said they were considering calling Slijkerman back in Kampala.

“Sophia pleaded with them not to do this,” Slijkerman said, apparently fearing her mother would worry about her, or that the trip would be aborted. The group went for another game drive that morning, and as there were no further incidents, the companions refrained from calling Koetsier’s mother.

Back at camp Koetsier paid a fine of 100,000 shillings (about $27) for the fire-damaged chairs. Meanwhile, Atubo decided to alter their travel plans due to Koetsier’s behavior. Instead of the small town of Kitgum, they would travel instead to the city of Gulu, which Atubo later told Slijkerman was “a more resourceful place.”

The group spent that night at a guest house in Gulu, where Koetsier took a room of her own. She said this was to get a good night’s rest, which may have been the case, though it is possible that tempers within the group were running high by this time.

“When Sophia is developing such an episode, she is not easy to deal with and tension can develop with those close to her,” Slijkerman said.

It’s also possible that Smeets and Van Dalen were surprised or taken aback by the suddenly heightened nature of her always extroverted personality.

According to her phone log, Koetsier spent that evening in Gulu talking and messaging with friends back in Amsterdam, including making plans for a New Year’s Eve soiree. She was last seen that night by a local man on the terrace of the guesthouse, shortly after midnight.

According to Slijkerman, who tracked down the man to interview him in 2017, Koetsier told him that she could not stay out late that night, as she had to be up early to make the trip to Murchison Falls.

Don’t Want to Die

The next morning, on the way to Murchison, videos shot in the car show Koetsier acting “normal and quiet,” according to Slijkerman.

Later, during a traffic jam on the highway, Koetsier gets out and walks about in the road, talking with the occupants of other vehicles. In the available video footage Koetsier “speaks a bit fast [and] asks many questions,” Slijkerman said.

When they return to the vehicle, Koetsier sits shotgun beside Mike, with Van Dalen and Smeets in the back.

A tense, emotional conversation ensues, and results in Koetsier breaking down in tears. In the video, she can be heard saying:

“Do you really think I’d be so stupid that I want to die, that I’m tired of life? I’m listening to what you’re saying, maybe I am interpreting it wrong, but that’s how I perceive it, the way you put it.”

About 15 minutes later Koetsier says: “Yes, I’m getting better.”

When the group stops for lunch, Koetsier again wanders off on her own. When Van Dalen goes to look for her, Koetsier is outside the restaurant, talking to a woman with a small child and shooting pictures and videos on her phone.

In one of the video clips, Koetsier can be heard telling Van Dalen, “Don’t follow me around all the time.”

After arriving at the park, the three women embarked on a boat tour of the falls aboard the African Queen, leaving at 2:30 that afternoon. Koetsier stayed on the lower deck at water level, while the other two chose to ride on the upper deck.

At 2:31 p.m., just one minute into the boat ride, Koetsier used her cellphone to call her mother in Kampala.

“She tells me she is on a boat, is very much enjoying everything and is, again, impressed by nature. She sounds calm,” Slijkerman said. Though the network was weak, this conversation nevertheless lasted approximately nine minutes. It was the last time Slijkerman would hear her daughter’s voice.

Other passengers reported that Koetsier spent about half of the trip in the boat’s toilet. She claimed an upset stomach, but Slijkerman believes she may have been seeking to avoid additional stimuli that might have felt overwhelming at the time because of her hyper-aware state.

“The toilet was, in retrospect, the only place where Sophia could separate herself from other people and the continuous new impressions, trying to find some rest and silence,” Slijkerman said.

Before reaching the falls, an incident occurred which would be the subject of intense speculation in the days and weeks to come.

The African Queen’s captain reported that Koetsier opened a hatch in the back of the boat behind the toilets. The hatch covered a small storage space that held two jerry cans with fuel.

“In spite of many rumors spread about this, there were no people who actually saw what happened except the captain, Dennis Okello, who says she fiddled with the cap of one of the jerry cans,” Slijkerman said.

“According to the girls it was Sophia’s intention to show that [the jerry cans] had not been stored away safely.”

Unfortunately, however, the Ugandan police seized on this moment to smear Koetsier’s character, and paint her behavior as erratic and irrational, perhaps to deflect from their own botched investigation and lack of initiative in the immediate aftermath of her disappearance. In other words, to once again blame the victim.

A Ugandan police report accuses Koetsier of attempting “to remove the fuel tank lid and tamper with the wiring system of the engine of the boat,” which is a far cry from the captain’s description.

In a particularly Kafka-esque turn of phrase, the report says that she had to be “restrained”—as though brute force or handcuffs had been required to keep her from scuttling the vessel. Nothing like that was reported by the captain or any of the other tourists aboard.

The same report also mentions Koetsier’s alleged “attempt to burn plastic chairs in the campfire” two nights before at Kidepo. And concludes by citing Koetsier’s “medical history” and “previous strange behavior” as prevailing factors in her disappearance.

Back on the boat, a group of American tourists reported that Koetsier was behaving quite normally when they arrived at the waterfall, shooting photos and enjoying the scenery.

A member of the crew, the lead tour guide, also recalled speaking with Koetsier at this time. He reported that it had been raining quite hard and she had asked him about how the rainfall impacted local wildlife and indigenous inhabitants of the park. The guide described it as a “normal and coherent” conversation, Slijkerman said.

Sophia Disappears

At the conclusion of the boat ride, likely worried about Koetsier’s mental state, Smeets told their driver that she and Van Dalen had decided not to continue traveling with her. Though they did not mention this to Koetsier herself, it seems quite plausible that she sensed her friends had reached such a decision—a move she may have interpreted as them having turned against her.

The party arrived at the UWA student center at about six in the evening. After settling into their cabins, Smeets used her cellphone to call Slijkerman, and inform her of their decision to end the trip and return to Kampala.

“I understood what she was saying and I told her not to inform Sophia of this plan as she would not agree to it, [that] she would resist.”

According to Slijkerman, the call lasted for 18 minutes. And it was during this time that Koetsier vanished. It’s possible Koetsier might have known or suspected that such a call had been made, and if this could have further heightened the strain in the party.

“We believe Sophia was aware of the plan of cutting the trip short which could have led to her walking off,” Slijkerman said.

After they realized she was missing, the friends instructed Atubo to start the car. They then put Koetsier’s favorite song—Isabella by Sauti Sol—on the car stereo, and left it playing on a repeating loop, in the hopes that she would hear the music and come back.

But she did not return.

Finally, after about two-and-a-half hours, at 9 p.m., Smeets called Slijkerman again and delivered the worst news any mother can ever hear. That her daughter had gone missing in the night and could not be found.

And so the nightmare began. The clothes and water bottle and personal effects found under such strange conditions. The callousness and incompetence of the law enforcement agencies on two continents pitted against the burning uncertainty in a mother’s heart.

A war of competing hypotheses and scenarios. An animal attack. A suicide. A swim in the dark gone wrong. A girl who wandered off and got lost.

Or, as Slijkerman has always thought, whether it was a chance encounter that turned into an abduction followed by a hamfisted attempt to make it look like something, anything else.

Slijkerman described the student center as having “no security” and “not really fit for tourists.” And, we now know, the area was full of people, including soldiers and UWA trainees.

“The [driver] was by then aware that Sophia was not well and it’s difficult to understand why he took them there,” she said.

‘Meant to Look Like an Animal Attack’

But now, after almost eight full years, it seems things could be moving. Because fresh analysis by experts in multiple fields indicates that Slijkerman’s maternal instincts may very well have been right all along.

As part of this investigation, The Daily Beast asked wilderness survival instructor Thomas Coyne to review all the available and relevant evidence, including witness testimony and photos in the case. Coyne founded and runs Coyne Survival Schools, one of the most respected programs of its kind in the world. He trains Marines, Air Force and Navy units, and assists law enforcement in their investigations. He’s not one of those reality TV stars with a gimmicky schtick and an outdoor clothing line named after him. Coyne makes Bear Grylls look like a webelo.

When asked about the possibility that Koetsier succumbed to an attack from a wild animal, Coyne offered a blunt assessment: “It is my belief that this is a homicide meant to look like an animal attack.”

One of the first pieces of evidence he flagged was the partial remains of Koetsier’s pants, which were found tied to and draped over shrubs and tree limbs.

“The clothing seems to be placed there so investigators would easily find it. The strips on the log made it obvious. She is not known to have been carrying a knife. This clothing was cut and then torn. A human can’t easily just tear a pair of pants to shreds.”

Coyne also agreed with Murchison ranger Buzu that placement of the clothing and other items—combined with the lack of human remains—also rule out the local fauna as suspects.

“Hippos don’t eat people, they crush and drown them. There would have been a body or pieces of it. Crocodiles eat you whole… [In that case] there could be bits of clothing in the scat, but they would have been larger and found along the banks according to river flow, not on land in very small strips.”

Coyne also shoots down the theory that Koetsier had drifted away from the student center and become lost, then used her clothes and other items as makeshift breadcrumbs to mark the way she’d gone.

The bits of clothing were not found in such a way as to indicate a potential signal effort, he said. If Koetsier had been flagging her path, the strips of cloth “would be tied on at eye level, not placed on logs on the ground.” Coyne also said people lost in the wild would not destroy or abandon “the clothing you need for environmental protection.”

Coyne observed that Koetsier was very close to the camp, and that her companions played loud music for her to find her way. “In the absolute quiet of the local jungle sound travels far. A proper whistle can be heard over one mile away in the right terrain. Considering where the articles were found, she would have heard the noise from camp and been able to head back,” Coyne said. Unless a person or persons had prevented this.

Coyne also said the location of the water bottle she had been using to collect trash indicates something happened to her swiftly, and that she did not merely wander off.

The finding of the trash-filled water bottle near the river bank shows she was not lost for a prolonged period of time. “Otherwise, she would have emptied the bottle to use it for drinking,” he said.

Coyne said that the finding of one clean boot but both insoles, as well as the empty purse and other items “seems to be part of the intentional spreading of clothing to simulate an animal attack.”

Finally, Coyne noted that the only articles of clothing recovered were related to Koetsier’s legs and lower extremities—i.e. her pants, underwear, boots, etc—but no garments from her upper body were found.

If a bladed weapon or blunt force head trauma had been used to subdue her, “it is likely the shirt contained blood from the victim, or possibly from the attacker if she fought back,” Coyne said.

‘Evidence Manipulation’

Criminologist Ferguson said that criminals are often hasty and clumsy in the immediate aftermath of a homicide, which could account for the confusing condition of the staged evidence in Koetsier’s case.

“If the crime is spontaneous in terms of timing, it is normal for them to make-do, using whatever evidence is available to create the false scenario. It is common for this to be done quickly, under stress, and therefore staging efforts of this type are often not well thought-out.”

When determining whether or not a staged abduction or homicide had occurred, Ferguson said she often “looks for elements of the victim’s background or the scenario which do not align with the alleged evidence.” For example, she mentioned “people who are not known to be suicidal suddenly becoming so without some major trigger.”

Ferguson added that this seems to be precisely the case in regard to Koetsier, as “there is little indication that Sophia was suicidal or a risk to herself.”

She said there were multiple elements in the evidence that seem to refute an accidental or suicidal scenario.

“The first is that it would be difficult, if not impossible for Sophia to find her way to the water in the twilight and alone. By itself, this makes it unlikely that she entered the water either by accident, falling in in the dark, or on purpose to swim or commit suicide,” Ferguson said.

“This is made even more unlikely by the fact that her co-travellers noticed she was missing quickly and appeared alarmed [and] began searching almost immediately. The timeline for her to get near the river, find it, and go in is therefore very limited—the searchers would be hurrying to locate her but there is no reason for her to have a similar sense of urgency.”

The condition of the recovered belongings also struck Ferguson as important.

“If Sophia somehow did this alone, in low light and quickly, there is no indication when, how or why her belongings were damaged and strewn around in the fashion they were found,” she said.

“The state of the clothing is not consistent with her accidentally falling in the water in low light in such a fashion that she could not self-rescue. If this were the case, I would expect her to still be clothed when she fell in.”

In conclusion, Ferguson said the evidence in the case “undermines both the accident and suicide scenario.” Like wilderness expert Coyne, she suspects foul play:

“The unlikelihood of an accidental or suicide scenario suggests homicide or abduction as likely alternative scenarios that need to be examined.”

And, like Slijkerman, Ferguson also said she wondered why the water bottle was located the day after Koetsier disappeared, but the clothes and other items weren’t discovered until a day later, despite being found just a few yards away.

“The two stage discovery of this evidence is suggestive of evidence manipulation by a third party, and further undermines both accidental and suicide scenarios.”

Unknown Man

Like Ferguson, the IFS’s DNA team also ruled out suicide, even taking into account the malaria medication Koetsier had been taking in combination with the “low (maintenance)” dose of her unipolar medication.

“The tearing of fabric and hanging a pair of knickers in a tree does not fit with suicide, whether or not under the influence of medication.”

On the contrary: “If Sophia were under the influence of such medication when she disappeared, this would increase the chance that she became the victim of a crime, also given the violent history of the country.”

Along with survivalist Coyne and staged homicide expert Ferguson, the IFS team also ruled out an animal attack or drowning. “The findings and DNA results above give very little support to a scenario in which Sophia Koetsier has fallen victim to an accident,” the team wrote.

And they ended the report by stating there is evidence to support the hypothesis that “Sophia Koetsier has been the victim of a crime.” Specifically, “that at least one unknown man, probably more, have been involved in the activities surrounding the disappearance of Sophia Koetsier.”

Caught in a Lie

After years of sleuthing; more than a score of return trips to Uganda; and tens of thousands of dollars spent, Slijkerman may have tracked down a very important witness whose account could point at a possible suspect.

While sifting through police reports in Uganda, she came across two statements given by a retired UPDF army officer who—to protect his safety and that of the ongoing investigation—we’ll call Captain Mukasa.

At the time Sophia went missing from the student center, Mukasa had been attached to the UWA as an instructor to train newly recruited rangers, according to the reports. In both of Mukasa’s statements, he mentioned that he had briefly interacted with a “white girl” who later turned out to have gone missing.

But Slijkerman caught a vital clue in Mukasa’s follow-up declaration to the cops, which indicated he wasn’t the only one who had encountered Koetsier just moments before she vanished.

“In the second statement, taken in 2020, he mentions a fellow officer he was with at that time and who also interacted with Sophia,” Slijkerman said. The other officer was identified in the report as a Captain Joseph (also a pseudonym).

Slijkerman realized that Joseph had never been questioned by police.

“I was very triggered by this information and immediately felt that I had to speak with both of them in person,” she said.

(The UPDF did not respond to our requests to speak with either of the two officers.)

Both men would prove difficult to track down as they had by now moved to other locations. But Slijkerman persevered.

She found Joseph first, in the fall of 2021. After such a long search, Slijkerman was disconcerted by her reception upon arriving at the barracks.

Slijkerman said that Joseph was “very evasive” toward her. He denied Mukasa’s statement to police that the men had been together at the student center and had met Koetsier there. Even claiming that he had never seen or spoken to Koetsier.

“[Joseph] was not eager to communicate and has not given any sign of changing his statement,” Slijkerman said, adding that at the time she was “very surprised that he contradicted his former colleague completely.”

Captain Mukasa proved harder to find. It wasn’t until February of this year that she tracked him to his home in a remote part of Uganda.

After driving all day with a friend to meet him, Slijkerman discovered Mukasa to be amiable and helpful. He repeated the same version of events he had given police, stating that he had been sitting on the porch with Joseph at the student center when Koetsier passed by and greeted them. She then asked them for directions to the latrine and walked in that direction. Mukasa even remembered the detail of the trash-filled water bottle she was carrying.

He also added another potential clue, saying that Joseph was strangely absent from the initial search efforts for her on the evening of her disappearance.

And so it seems someone is lying about where he was that day and who he was with.

“When I spoke with [Mukasa], I was accompanied by a Ugandan friend. We both thought he was sincere,” Slijkerman said. She also said Mukasa “has no explanation for why Joseph is denying [that he spoke with Sophia].”

The Daily Beast spoke with the friend who accompanied Slijkerman. He works for an international NGO that assists with human rights issues in Uganda, and in fact he had been vital in helping her locate Mukasa. Because of the nature of his humanitarian work, he asked to remain anonymous. But what he said corroborates the details of Slijkerman’s meeting with Mukasa.

“I agree with Marije that [Mukasa was sincere],” said the NGO officer, who described Mukasa as “honest, open, and kind” as well as “welcoming and empathetic.”

Mukasa had a “good recollection of events before and after [Sophia’s] disappearance” and spoke “freely” and “without holding back,” he said, and added that he was shocked and baffled by Major Joseph’s conflicting version of events.

“[He] was visibly surprised and, I’d say, confused, to hear that [Major Joseph] denied having interacted with Sophia. According to him, [Joseph] even asked Sophia if she needed a trash can [in which to empty her] plastic water bottle filled with trash,” the human rights worker said.

“He really didn’t seem to get why [Joseph] was contradicting his account. He described the moments when they interacted with Sophia and emphasized that [Joseph] was with him at that moment. And that they were relaxing outside their room after the day’s drill.”

Slijkerman has since alerted the Ugandan investigators to the discrepant testimonies from the two officers, but the CID remains stubbornly opaque.

“I am assuming that the police, by now, have also spoken with [Joseph] but as I am not currently privy to any findings of this investigation, I can’t tell what they have been doing with this [lead].

The Dutch homicide detective said that he’s not surprised the initial investigation didn’t make much headway in identifying a suspect. Without a prior connection to the victim to establish motive, many murders involving complete strangers often go unsolved.

“One of the main reasons why these cases become cold cases is that there is often no clear relationship between the perpetrator and the victim,” he said.

After so much time spent probing in the dark, a possible hypothesis seems to have taken shape with the disparate pieces finally falling into place: Koetsier was experiencing a manic episode due to travel-related stress and lack of sleep. Driven away from the camp because of stress within her group, she may tragically have crossed paths with the wrong person or people—whoever that might have been.

And so it seems her outgoing nature, heightened by her condition, may have made her easy prey for someone local, especially if they had first-hand knowledge of the area.

To Catch the Culprit

What happens next depends largely on the response of the CID and Director Magambo, and if they decide to follow up on the new lead Slijkerman has uncovered.

Slijkerman stated that the Ugandan authorities were helpful in tracking down Joseph, and hopes the CID will investigate further. And she is planning yet another return to Uganda later this year.

“Statistically speaking, the longer someone is missing, the slimmer chances are they will be found. We know that. But I am and remain a staunch believer in miracles. They happen,” she said.

From a law enforcement perspective, the Dutch detective offered us a laundry list of what he thinks should happen, if the CID wants to prove its bona fides. His list included:

• Make clear to the Ugandan public which of the garments Koetsier was wearing at the time were not found at the crime scene, since perhaps someone else has come across these garments elsewhere.

• Compare the recovered DNA with as many men as possible who were in the vicinity of the crime scene.

• Thoroughly depose all those who were in the vicinity of the location where Koetsier was last seen.

• Make sure that DNA is taken from all unidentified human remains that are found in Uganda and that it is compared with Koetsier’s DNA and, of course, that of other missing persons.

Queensland University’s Ferguson agreed with the detective. “Given Sophia’s known propensity for being friendly and speaking with strangers when she was in a manic state, I would suggest documenting and interviewing [all the rangers and soldiers who were present].”

Regardless of what the authorities do or don’t do, Slijkerman’s unflagging determination to seek the truth will remain unchanged.

“People don't like stories with an open end. They tend to make up an end themselves so they can leave it and move on. But we cannot move on,” Slijkerman said. “There is nothing to process, our trauma continues. Every day. And maybe for the rest of our lives.”

Read more at The Daily Beast.

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