PORTLAND, Oregon (AP) — A United States (US) off-duty airline pilot riding in an extra cockpit seat on a Horizon Air flight said “I’m not OK” just before trying to cut the engines mid flight and later told police he had been struggling with depression, according to charging documents made public Tuesday.

State prosecutors in Oregon filed 83 counts of attempted murder against Alaska Airlines pilot Joseph David Emerson, 44, on Tuesday just before he appeared in court, with his attorney, Noah Horst, entering not guilty pleas on his behalf. Federal prosecutors meanwhile charged Emerson with interfering with a flight crew, which can carry up to 20 years in prison.

According to a probable cause statement filed in Multnomah County Circuit Court, Emerson told Port of Portland police following his arrest that he had been struggling with depression, that a friend had recently died and that he had taken psychedelic mushrooms about 48 hours before he attempted to cut the engines. He also said he had not slept in more than 40 hours, according to the document.

Police reported that Emerson did not appear to be intoxicated at the time of the interview, and in a statement Tuesday, Alaska Airlines, which owns Horizon, said neither the gate agents nor flight crew noticed any signs of impairment that might have barred him from the flight. An FBI agent wrote in a probable cause affidavit in support of the federal charge that Emerson “said it was his first-time taking mushrooms.”

While psilocybin is illegal in most of the country — Oregon legalised it for adults this year — the Food and Drug Administration in 2018 designated it a “breakthrough therapy” that might be used for mental health conditions or substance use disorders.

Emerson, an Alaska Airlines pilot from Pleasant Hill, California, was arrested Sunday night after the flight crew reported that he attempted to shut down the engines on a Horizon Air flight from Everett, Washington, to San Francisco while riding in the extra seat in the cockpit. The plane was diverted to Portland, where it landed safely with more than 80 people on board.

The FBI affidavit said Emerson, who as an off-duty pilot was authorised to ride in the cockpit’s jump seat, made casual conversation with the captain and first officer when the plane was between Astoria, Oregon, and Portland, before trying to grab two red handles that would have activated the plane’s fire suppression system and cut off fuel to its engines.

After what the flight crew described as a brief struggle, lasting only about 30 seconds, Emerson left the cockpit, the FBI said.

Flight attendants placed Emerson in wrist restraints and seated him in the rear of the aircraft, but as the plane descended, he tried to grab the handle of an emergency exit, according to the document. A flight attendant stopped him by placing her hands on top of his, it said.

Alaska Airlines said Tuesday that Emerson had been relieved of all duties.

Horst did not immediately speak with reporters following the hearing or respond to phone and email messages seeking comment.

The captain and first officer told police after the plane landed that Emerson said “I’m not OK” just before he reached up to pull the handles. They were able to stop him before he pulled the handles all the way down, the affidavit said.

Emerson walked calmly to the back of the plane after being told to leave the cockpit and told a flight attendant, “You need to cuff me right now or it’s going to be bad,” the affidavit said. Another flight attendant heard him saying, “I messed everything up” and “tried to kill everybody.”