At least 3 factors may have contributed to diver's death at Missouri spring, report finds

Investigative documents detailing the events surrounding a diver's death at Roaring River State Park show that multiple factors likely contributed to the drowning deep inside a cave spring.

Eric Hahn was diving with the KISS Rebreathers team in October 2022 and was more than 100 feet underwater in the cave when he drowned. Law enforcement were notified and helped supervise recovery of his body.

Investigators initially speculated that the cause of death was due to equipment malfunction. However, documents released by the Missouri State Highway Patrol following a public records request by the News-Leader indicate there were "several likely contributing factors" that lead to the 27-year-old's death.

In the records released to the News-Leader, the names of Hahn and other divers were sometimes redacted, but the News-Leader was able to determine when the reports referenced Hahn based on context.

More:Diver drowns in Roaring River spring; Highway Patrol investigating

Eric Hahn and another diver were planning two dives, timeline shows

Hahn and another diver had a plan before entering the water, according to the documents. They were going to dive down and place safety tanks along the navigation guideline that was already secured in the cave ahead of a dive taking place the next day.

A topside manager recorded the divers' descent at 11:12 a.m. Oct. 14, 2022, along with the gas mixture in their tanks and the amount measured in PSI, or pounds per square inch.

Both divers descended to 70 feet, clipped four tanks on the line and returned to a shallow depth, but did not exit the water. One diver's computer recorded this as dive No. 1 and did not reset, but the other's computer reset and recorded the dive as No. 2 (it was not clear from the documents which computer was Hahn's). The divers took three more safety tanks and began their descent once more.

As they approached the 190-foot mark, Hahn and his companion passed another pair of divers who were in the process of ascending towards the surface. Once at their mark, Hahn and his fellow diver finished attaching the tanks at 190 feet.

About five minutes into their second dive, at approximately 11:25 a.m., one diver started to return to the surface when he felt his partner, Hahn, bump into him. The diver told law enforcement officials later that Hahn started swimming straight up and was impacting the cave's ceiling.

The diver could tell Hahn was panicking and went over to assist him, but Hahn kept trying to swim straight up. The diver grabbed Hahn at around 165 feet and saw that he was yelling. It looked like Hahn was trying to get his rebreather mouthpiece out of his mouth, according to the report.

The diver grabbed a bailout first stage regulator that was around Hahn's neck. The regulator was connected to a diluent tank (used to dilute the oxygen mix a diver breathes) on Hahn's left side. The diver placed the regulator in Hahn's mouth as he spit out the rebreather mouthpiece, according to the documents.

Hahn began seizing, and the other diver tried to manually purge the regulator so Hahn could breath from it. At this point, both divers had dropped to the cave floor, about 201 feet below the surface.

Once Hahn became unresponsive, the other diver attempted to inflate both of their buoyancy compensators to help get off the floor of the cave, but he could not move Hahn.

"(The diver) made the decision to go back towards the surface and get additional help from (the other divers) who were still decompressing at a shallower depth," the documents stated.

At 100 feet, Hahn's partner met up with another diver and told them that Hahn was unresponsive. That diver went down and tried locating Hahn as the partner continued to ascend. The partner made contact with another person at 40 feet, who then went to contact emergency services. The partner once again descended back into the cave and met with the other diver at 150 feet. They attempted to recover Hahn but were not able to because of oxygen problems they were experiencing, documents stated.

Both divers completed their decompression stop and exited the water.

At approximately 4 p.m., the KISS Rebreather dive team planned their recovery operation, under the supervision of the Missouri State Highway Patrol. The team located Hahn's body and gear at 201 feet. Because of the long decompression stops, Hahn's body was handed to another set of divers at 70 feet.

Once returned to the surface, Hahn's body was released to the Barry County Coroner and his equipment was turned over to law enforcement for examination.

One person interviewed by law enforcement was asked about maintenance and analysis procedures of their dive gear. The interviewee said each diver is responsible for the maintenance of their own gear. He was also unsure when the gear was last maintained or when the gas in the tanks was filled or analyzed. The man said Hahn "most likely filled his tanks back home" at the Scuba Club of Virginia Tech in Virginia and analyzed them after.

There were at least three contributing factors that may have led to diver's death

After collecting samples from the air tanks and examining Hahn's equipment, a supplemental report detailed what the contributing factors may have been in his death.

The first likely contributing circumstance involved the gas inside of a tank at Hahn's left side, according to the report. The gas contained an approximately 26% oxygen mix, which is determined by using a scientific calculation based on the oxygen concentration in the dive tank and the depth.

Based on that mix, "The victim exceeded his maximum operating depth during the dive," the report stated.

When exceeding those depths, divers can experience what's known as central nervous system, or CNS, oxygen toxicity "due to breathing high concentrations of oxygen." In a 2006 article published by National Library of Medicine regarding CNS in a closed-circuit diving incident, some symptoms that appeared included limb convulsions, hyperventilation, difficulty maintaining a steady depth, headache and visual disturbances.

Investigators analyzed Hahn's dive computer and saw that another likely contributing factor could have been that he was adding small amounts of 100% oxygen to his rebreather unit during his dive. This caused his partial pressure of oxygen to increase, which changes with depth during a dive and is monitored and corrected by adding oxygen or diluent gas on rebreather units, the report explained.

Because Hahn both exceeded his maximum operating depth and added additional oxygen to his rebreather, his Partial Pressure of Oxygen climbed to 1.8 ATA, or atmospheres, around 190 feet deep. This partial pressure "likely caused the convulsions and seizures that are symptoms" of CNS oxygen toxicity, according to the patrol documents.

Nitrogen narcosis was the third factor identified as a likely contributor in Hahn's death. Helium is often added into dive mixtures to reduce nitrogen exposure on the body and to help decrease narcosis — drug-induced stupor or drowsiness — the report stated. Divers can experience narcosis when descending to deeper depths, and they can experience loss of fine motor skills and impaired judgement.

Hahn's tank on his left side was analyzed at 26.9% oxygen and 0% helium mix.

"The lack of helium in the victim's gas mixture could likely cause narcosis at or before the 190-foot depth," the report stated. "The high (Partial Pressure of Oxygen) levels uncorrected by the victim along with the victim continuing to dive deeper into the cave could likely be caused by impaired judgement from narcosis."

Eric Hahn spoke with a KSMU reporter about diving experiences two months before his death

In August 2022, Eric Hahn spoke with KSMU reporter Michele Skalicky. Hahn explained his roles on the dive team, which included collecting cave animals to study. Hahn said in the interview he had gone past the restriction point on multiple occasions.

Hahn told Skalicky that cave diving allowed him to go where few people have gone before.

"You know, fewer people have gone through this one location than have even been on the moon," Hahn said in KSMU's report. "The equipment considerations and the environments are very different, but at the same time, we each have entire life support systems that keep us breathing, keep us warm, keep us alive."

Sara Karnes is an Outdoors Reporter with the Springfield News-Leader. Follow along with her adventures on Twitter and Instagram @Sara_Karnes. Got a story to tell? Email her at skarnes@springfi.gannett.com.

This article originally appeared on Springfield News-Leader: Investigative reports ID factors in diver's death at Missouri spring