Phoenix, Fla. (AP) — Authorities trying to determine whether drugs were involved in the Fata hot air balloon crash in Arizona released a revised autopsy report that says Frieda was given an anesthetic drug given to the pilot by an air ambulance companion. Was given while he was being taken to the hospital.

The Pinal County Medical Examiner's Office said earlier this week that toxicology tests showed Cornelius Van der Walt had high levels of ketamine in his blood after the fatal Jan. 14 crash that killed him and three passengers. but did not specify how it got into their system. Or when.

The revised report released Friday answered the question, clarifying that the ketamine was administered by the company that transported Van der Walt to the hospital.

The balloon, operated by Dropline Hot Air Balloon Rides, dropped approximately 2,000 feet (609 m) to the desert floor south of Phoenix near Eloy.

Investigators have not yet determined the cause of the accident.Neither Eloy Fire Department paramedics nor hospital staff administered ketamine, with no other significant changes, according to the updated report.

While in recent years more clinics have offered ketamine as a treatment for pain, depression, anxiety and other conditions, the report said Van der Walt is not aware of any ketamine prescriptions issued.

The report cites a study outside the US that found that amounts of ketamine – higher than the amount measured in van der Walt's blood – are a sign of impairment in drivers. Adverse reactions may include hallucinations, blurred vision, irrational behavior, nausea, and seizures.

A preliminary report from the National Transportation Safety Board earlier this year said there was damage near the top of the envelope, where the sewn rim tap material was worn out, and several panels of the balloon were damaged. That envelope is filled with hot air, causing the balloon to rise.When the Kubicek BB 85Z balloon took off from Eloy in the morning, there were thirteen people on board. There were eight skydivers who exited the Gondola before the accident.

Skydivers jumped from a height of approximately 5,000 feet (1,524 m). Witnesses said the balloon partially deflated and began losing altitude rapidly before crashing into an empty field, which serves as a drop zone for skydivers.

Van der Walt, 37, and three passengers died, including Caitlin "Katie" Bartrom, 28, of Andrews, Indiana; Chayton Viskolek, 28, of Union City, Michigan; and Atahan Kilikkot, 24, of Cupertino, California, another woman seriously injured in the crash.

Dropline Hot Air Balloon Rides wrote on its website that its safety record was perfect before the accident and that it has since closed operations at its only two sites in Eloy and Utah.