28-year-old Washington State University grad student arrested in University of Idaho killings

A suspect in the brutal slayings of four University of Idaho students — crimes that have "shaken our community" — was arrested in Pennsylvania, authorities said Friday.

Bryan Christopher Kohberger, 28, a resident of Pullman, Washington, was apprehended in Albrightsville in northeastern Pennsylvania, about 2,500 miles from the Idaho campus, officials said.

He'll be charged with four counts of first-degree murder and burglary, for allegedly breaking into the Moscow, Idaho, home with the intent to commit a felony, authorities said.

DNA evidence played a key role in linking the murders to Kohberger, two law enforcement sources familiar with the investigation told NBC News.

The shocking crimes have captivated the nation during these past seven weeks, generating about 19,000 tips from the public that police said were crucial to the probe.

"These murders have shaken our community and no arrest will ever bring back these young students," Moscow Police Chief James Fry told reporters in Idaho. "However, we do believe justice will be found through the criminal process."

Ethan Chapin, 20, of Conway, Washington; Madison Mogen, 21, of Coeur d’Alene, Idaho; Xana Kernodle, 20, of Avondale, Arizona; and Kaylee Goncalves, 21, of Rathdrum, Idaho, were killed on Nov. 13.

Three of the victims shared the home in which they died — Goncalves, Mogen and Kernodle — while Kernodle’s boyfriend, Chapin, was staying overnight, according to investigators.

Kohberger is due back in court in Pennsylvania on Tuesday when he’ll opt to fight or waive extradition to Idaho, according to Latah County prosecuting attorney Bill Thompson.

Washington State University Provost Elizabeth Chilton said the murders have “shaken everyone in the region,” which includes overlapping college communities, and she thanked law enforcement for making an arrest.

In a statement Friday evening, Washington State University said Kohberger is a graduate student at its main campus, 9 miles from Moscow.

The institution said it assisted investigators with the execution Friday morning of search warrants at his on-campus apartment and office.

The suspect is a doctoral student who completed his first semester in criminal justice, the university said.

By nightfall, forensic experts were inside a second-floor student apartment in Pullman that was cordoned off with yellow police tape. Local authorities were also on the scene standing watch.

Justin Williams, 34, who lives in the same building as the taped-off apartment, said he found out about the suspect after two FBI agents knocked on his door earlier in the day.

During the 15 minute questioning, Williams told them he’d only crossed paths with Kohberger once — last June when he saw Kohberger checking his mailbox.

At the time, he said nothing seemed out of the ordinary, but the two didn’t speak.

“He didn’t act weird. He just seemed quiet and kept to himself,” Williams said. “Everyone usually just sticks to themselves. But he lives right next to me and I have kids.”

Aryan Deshwal, another apartment resident and graduate student, said Friday night the stabbing has stressed out the complex's residents.

“It’s so scary right now,” he said, adding that the four murders have dominated conversations among residents, even over the holiday break.

“The killings have been hovering over the community," he said.

Prosecutor pleads for more tips

The prosecutor said investigators were still in need of more information and pleaded with Idaho residents to come forward with anything they knew about  Kohberger.

“This is not the end of this investigation,” Thompson said. “In fact, this is a new beginning.”

Investigators still need the public's help to “understand fully everything there is to know not only about the individual but what happened and why," according to Thompson.

Police and prosecutors on Friday revealed few details about the arrest, such as a possible motive, how the suspect might know the victims and what tips or evidence first led detectives to Kohberger.

A probable cause affidavit, with details supporting Kohberger's arrest, is sealed and cannot be made public until he sets foot in Idaho and is served with those papers in court, authorities said.

Fry, the police chief, appeared to say that Kohberger is the only suspect in this case.

“What I can tell you is that we have an individual in custody who committed these horrible crimes and I do believe our community is safe," he said.

The "sleepless" nights for police before arrest

Authorities in Idaho thanked the FBI and Pennsylvania state police for their help in taking Kohberger into custody.

Fry appeared to admit there were several days between the moment detectives concluded Kohberger was their suspect and the time when handcuffs were finally placed on the graduate student.

“I can tell you, for a lot of law enforcement,  it was a fairly sleepless couple of days," the Moscow police chief said.

A Hyundai Elantra was taken away from the person's home in Pennsylvania on Friday, law enforcement sources said.

Police in Moscow had been looking for a white Hyundai Elantra as a possible piece of evidence.

Arrest a "huge weight" off loved one's shoulders

The mother of one of the four students told NBC News on Friday that a huge weight had been lifted with the arrest of a suspect.

Cara Northington, the mother of Xana Kernodle, said she learned of an arrest after waking up and speaking to a friend. All she has been able to think about is who would have killed her daughter and her friends as she held out hope that there would be a break in the case.

“It’s been a nightmare. This whole thing has been a nightmare, literally,” Northington said. “But I feel like a huge weight has been lifted off my shoulders.”

She added that she is unfamiliar with the person who was arrested Friday in Pennsylvania, but is relieved he was apprehended.

“A lot of the grief was not knowing who this was, knowing that whoever was responsible for that is still out there,” she said. “So yeah, this definitely takes a lot of the grief that we were experiencing off our shoulders.”

Northington said she’s also grateful to the support from strangers across the country and to law enforcement. Authorities believe they were killed inside the apartment house while they slept, although some had defensive wounds.

Police were also still looking for the weapon, believed to be a large knife, Frey said Friday.

Two other roommates were home at the time of the slayings in the early morning of Nov. 13, but police said they were not believed to have been involved in the crime.

They were asleep during the stabbings, and one of their cellphones was used to call 911 when they woke up later that morning, detectives said.

The investigation has been led by Moscow police, with dozens of state and federal agents providing forensic analysis of a scene that experts say had been complicated by the nature of the crime — a quadruple homicide — and the fact that the roommates would host parties.

As weeks went by without an arrest or a person of interest named, the case drew attention from internet sleuths, leading police to dispel unfounded claims on social media.

Fry insisted that the case was not cold.

He also declined to speak in detail about the case or investigators’ best leads, telling NBC News last week that police must protect the integrity of the investigation and didn't want to taint a potential jury pool if there was a trial.

“I know that’s very frustrating,” Fry said. “It’s frustrating to family members and [the] community, but our end goal is to bring somebody to justice for those families and for those victims.”

The case was initially dogged by mixed messaging from authorities, who first told the public that the “targeted attack” posed no lingering threat to the community. But Fry, days later, said he couldn’t say where the killer or killers may be.

Keeping quiet was correct way to go, chief says

Fry on Friday defended his handling of the case, saying it was crucial to keep information "very, very tight.”

“One-hundred percent, (we) will stand behind how we handed this investigation," Fry said. “We want to have a situation where when this goes to trial there is no doubt that we did everything right.”

An arrest comes as a “celebration of life” was planned later Friday for two of the roommates, Goncalves and Mogen.

Shanon Gray, a lawyer for Goncalves’ loved ones, said of his clients: “The family is relieved that the authorities have someone in custody and now the journey through the criminal justice system begins.”

This article was originally published on NBCNews.com