A man has been arraigned in a Hawaiian court for the aggravated sexual assault of a passenger on a Japanese airlines flight. The plane had to turn back due to the gravity of the situation.

The incident involving Hawaiian Michael Tanouye, 29, took place on Saturday during a flight from Honolulu to Kansai, Japan. Tanouye, according to an affidavit released by an FBI spokesman, allegedly forced himself into a lavatory on the plane just moments after a Japanese female had entered. He then proceeded to forcefully undress the woman and “also began to take down his pants and underwear, exposing his penis,” according to the document, as cited by AP.

The victim pushed back at the man and was able to press the emergency button inside the lavatory.

The victim’s mother had seen Tanouye enter the lavatory and advised flight attendants of the situation. The mother, a flight attendant and other passengers tried to force the door open, but were only able to gain entry by removing the screws from the hinges, and then subdued Tanonuye. A passenger was injured in the process of subduing the accused.

Shortly before the incident Tanonuye had stood up to walk around, appearing at first calm, then telling flight attendants he was off to visit his grandmother.

Apparently, he was then heard shouting something that witnesses could not make out, prior to allegedly forcing his way into the lavatory. His mother earlier told flight attendants the young man was on medication for depression. A decision was made not to serve him alcohol.

Once the accused was subdued, his mother gave him a dose of his medication, which made him fall asleep, according to the affidavit.

Because of the incident the flight was forced to return to Hawaii, where the FBI took Tanouye into custody. He was held in a federal detention center in Honolulu and charged on Tuesday with interfering with a flight crew and aggravated sexual assault aboard an aircraft.

The FBI says the statutory maximum penalty for interfering with a flight crew is 20 years in federal prison, and the statutory maximum for the other charge is a life sentence.