A man who assaulted a fellow passenger aboard a Japan Airlines flight and attempted to sexually assault another passenger was found not guilty in U.S. District Court today by reason of insanity.

The FBI says Michael Tanouye forced his way into a lavatory with a female passenger Oct. 11, 2014 and attempted to sexually assault her, then injured another passenger who, along with flight attendants and other passengers, was able to remove the lavatory door and subdue Tanouye.

JAL pilots turned the plane around and returned to Honolulu following the incident. The airplane had been less than two hours into its flight to Kansai International Airport.

Tanouye doesn’t dispute the FBI’s account of what happened aboard JAL flight 791.

His lawyer Rick Sing presented the court with medical and psychiatric reports prepared by federal prison staff that say Tanouye was suffering from a severe mental disease at the time and is therefore not legally responsible for his actions.

The FBI says Tanouye’s mother told flight attendants that her son suffered from depression and was on medication.

U.S. District Judge Derrick K. Watson found Tanouye not guilty by reason of insanity and set a hearing for April to determine whether or not he should remain in custody for the protection of others.

Tanouye has been in custody since his arrest in October 2014.