An American Airlines passenger whose odd behavior aboard a Honolulu-bound flight prompted the captain to call for military fighter jet escort is scheduled to plead guilty Tuesday in U.S. District Court.

Anil Uskanli is charged with interfering with members of a flight crew and attendants. The maximum penalty is 20 years in prison. His criminal lawyer Richard Sing confirmed Wednesday that there is a plea agreement but would not disclose details of it.

When Uskanli boarded the airplane in May on a flight from Los Angeles to Honolulu, he attempted to sit in the first-class section before being escorted to his assigned seat farther back in the aircraft. The FBI said Uskanli caused a disturbance during the flight after another passenger walked in on him through an unlocked bathroom door.

The FBI said flight attendants became alarmed when Uskanli headed back to the front of the aircraft carrying his laptop computer. The flight attendants feared the computer may contain explosives, the FBI said. That fear prompted the attendants to barricade the laptop in the back of the plane, the captain to fly at a lower altitude and the scrambling of two Hawaii National Guard fighter aircraft from Joint Base Pearl Harbor-­Hickam.

Uskanli, 25, is a Turkish citizen who was in the United States on a student visa. U.S. Immigration officials have revoked the visa and placed a detainer on Uskanli to keep him in custody should he get released in his criminal case.

Gary Singh, Uskanli’s immigration lawyer, said following Tuesday’s guilty plea, Uskanli will tell immigration officials that he will agree to leave the country as soon as he completes whatever sentence he receives in the criminal case.

Uskanli has been in custody since the FBI arrested him May 19, when his flight landed in Honolulu.

At Uskanli’s bail hearing last Thursday, Sing said Uskanli was diagnosed with a mental illness in Turkey in 2015. Uskanli was not in possession of any prescription medication when he was arrested but the FBI said benzodiazepine, a drug used to treat anxiety disorders, panic and agitation, was found in his system.

Sing said Uskanli could have been experiencing the onset of another mental condition last May because the diagnosis of the forensic psychologist who recently examined Uskanli in a U.S. Bureau of Prisons facility in Nevada is different from the 2015 diagnosis.

A federal judge ordered the examination to determine whether Uskanli had the mental competency to stand trial. U.S. Magistrate Judge Kenneth J. Mansfield declared Uskanli competent Sept. 21 but ordered him to remain in custody because he had threatened to kill an FBI agent and his mental competency examiner, threatened to burn down a federal detention center in Los Angeles where he was held briefly, and tried to flee while in custody.

The FBI says Uskanli purchased a plane ticket to Honolulu at an airline counter at the Los Angeles International Airport in the middle of the night with no checked or carry-on luggage. Before boarding, he was cited for entering a restricted area then escorted to the gate because officials believed he was under the influence of drugs or alcohol.