PHOENIX — The pilot of a hot air balloon that crashed in Arizona and left four dead had elevated levels of ketamine in his system, according to an autopsy and toxicology report.

Cornelius van der Walt, 37, of Eloy, Arizona, was piloting the aircraft when it fell in January. He and three other people — Chayton Wiescholek, 28, of Union City, Michigan; Kaitlynn Bartrom, 28, of Andrews, Indiana; and Atahan Kiliccote, 24, of Cupertino, California — died in the crash. One other passenger was seriously injured.

The balloon, a Kubicek BB 85, was operated by Droplyne Hot Air Balloon Rides and was manufactured in 2011. Van der Walt, originally from South Africa, was the owner of the company.

The balloon had been carrying 13 people at takeoff. Eight of them were skydivers who had left the craft before issues arose.

Those who knew van der Walt described him as experienced and safety-minded. But two toxicology panels — one conducted by NMS Labs on behalf of the Pinal County Medical Examiner's Office and another by the Federal Aviation Administration — found ketamine in his blood.

Van der Walt didn't have a known ketamine prescription, and the drug wasn't used in resuscitation efforts at the scene of the crash, according to the report.

A toxicology panel found his blood ketamine content was about 60 times the threshold established by the United Kingdom as being indicative of impaired driving. A threshold for impairment was not immediately available from a U.S. source.

"In overdose, ketamine produces effects such as hallucinations, delirium, irrational behavior and vision and GI disturbances, progressing to cardiovascular and respiratory irregularities," NMS labs staffers wrote in their toxicology report.

The rest of van der Walt's autopsy notes severe injuries he sustained during the hot air balloon crash. His head had "large scalp contusions," according to the report. He also suffered numerous rib fractures, muscle injuries, a brain hemorrhage, and abrasions all over his body. The autopsy states those combined injuries led to his death.

Investigators are continuing to probe the incident.

'Balloon was descending with a deflated envelope'

The balloon went down after an "unspecified problem" with its "envelope" — the large bag that fills with hot air to make the aircraft rise, according to a Jan. 15 statement from the National Transportation Safety Board.

The federal agency on Jan. 25 released a preliminary report stating that before the balloon hit the ground, the craft was already deflated with the burner on.

"A review of multiple mobile phone videos revealed that the balloon was descending with a deflated envelope trailing from above," the report read. "Additionally, at times the burner flame under the envelope was observed."

The report also showed thermal damage near the mouth of the envelope. Sewn rim tape material at the top of the envelope was frayed and several panels were damaged.

The NTSB says investigations can take one to two years before they're complete and a final report is available according to its website.

What is ketamine?

Ketamine is a dissociative anesthetic that can cause hallucinations, according to the Drug Enforcement Administration. The agency says the dissociative aspect comes from its ability to make users feel as though they’re detached from their pain and the environment around them.

The DEA said that, unlike LSD or PCP, the hallucinatory effects of ketamine only last around 30 to 60 minutes rather than several hours. But Hallucinogen Persisting Perception Disorder, or HPPD, has been reported by ketamine users several weeks after using the drug.

Users typically feel its effects within minutes of taking ketamine, which can be taken in the form of powder that is ingested or snorted, or a liquid form that’s either injected or taken orally.

The FDA approved ketamine to be used as a general anesthetic, but has been known to also be prescribed to treat depression, though that's an "off-label" use the FDA hasn't approved. The DEA says ketamine is also a popular "club drug" used by teens and young adults recreationally. 

According to American Addiction Centers, a nationwide network of rehab facilities, ketamine has a half-life — the time it takes for a drug in the body to be reduced by 50% — of about two and a half hours in adults. The majority of the drug is out of one's system after about 10 to 12 hours.

The National Library of Medicine states ketamine prescriptions often include information warning users not to operate heavy machinery or perform potentially hazardous activities for 24 hours after taking the drug.

Recovering:Survivor of Arizona hot air balloon crash on 'long road of rehabilitation,' parents say

Services suspended due to crash

Ian Gregor, a Federal Aviation Administration spokesperson, said he was still working on finding out if the agency had any policies about ketamine use among pilots, but he cited regulations that stated crew members of a civil aircraft could not use any drug that "affects the person's faculties in any way contrary to safety."

Droplyne Hot Air Balloon Rides could not be reached for comment. According to a statement on their website, services have been suspended due to the tragic crash.

"Given the recent incident on 14 of January, we have abruptly halted all services, digital and physical. This has been nothing short of a shock for all those involved, so forgive us for not being able to process your requests in a more timely manner," the statement said.

Sasha Hupka covers county government and regional issues for The Arizona Republic. Do you have a tip to share? Reach her at sasha.hupka@arizonarepublic.com. Follow her on X, formerly Twitter: @SashaHupka. Follow her on Threads: @sashahupkasnaps.

Perry Vandell is a public safety and breaking news reporter for The Arizona Republic. He can be reached at perry.vandell@gannett.com. Follow him on X, formerly known as Twitter: @PerryVandell.

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