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Four people were killed and one person was critically injured after a hot air balloon crashed in Arizona in January.
CNN  — 

The pilot of a hot air balloon that crashed in Arizona in January, leaving four people dead, had high levels of the psychedelic drug ketamine in his blood system, according to a forensic examination report from the Pinal County Medical Examiner’s Office.

The autopsy report initially said Cornelius van der Walt, 37, had no reported prescription for ketamine, and the drug was not used during resuscitation attempts. But the report was revised on April 5 to indicate ketamine was indeed administered during lifesaving measures.

Van der Walt had ketamine levels of between 1.1 to 1.2 mg/L in his system, according to toxicology testing from the FAA and from NMS Labs. For comparison, the United Kingdom considers ketamine levels over .02 mg/L to be indicative of impaired driving ability, the report says.

The report ultimately determined the cause of death was multiple blunt force trauma and the manner of death was accident.

Ketamine is a dissociative anesthetic with hallucinogenic effects and makes users feel detached and disconnected from their pain and environment, according to the US Drug Enforcement Administration. The drug has also proven to be helpful for treating depression and trauma, and a derivative of the drug called esketamine was approved by the US Food and Drug Administration in 2019 for some patients with depression.

The medical examiner’s report stems from the hot air balloon crash in Eloy, Arizona, on January 14 in which the pilot and three other people were killed.

The aircraft was carrying 13 adults in all, including a pilot, four passengers and eight skydivers. After the skydivers safely jumped from the basket of the aircraft, there was a catastrophic problem with its envelope – the part of the craft that looks like a balloon – that caused it to crash to the ground, authorities said.

Witnesses and cell phone video showed the hot air balloon was falling with a deflated envelope trailing from above, with the burner flame at times still on, according to a preliminary report from the National Transportation Safety Board, which is investigating the crash.

“The envelope remained attached to the basket and showed thermal damage near the mouth of the envelope,” the NTSB’s preliminary report states. “The sewn rim tape material near the top of the envelope was frayed, and several of the panels were damaged.”

Police identified the four victims as van der Walt, who lived in Eloy; Chayton Wiescholek, 28, from Union City, Michigan; Kaitlynn Bartrom, 28, from Andrews, Indiana; and Atahan Kiliccote, 24, from Cupertino, California.

Valerie Stutterheim, a 23-year-old from Scottsdale, Arizona, was critically injured in the incident, police said.

The aircraft was an A-160 passenger balloon manufactured by Cameron Balloons, according to the NTSB. The model can carry a pilot and up to seven riders, the manufacturer’s website says.

CNN’s Melissa Alonso contributed to this report.