A Cook County judge Monday ordered a mental fitness evaluation for Marilyn Hartman, the 68-year-old “Serial Stowaway” facing jail time for allegedly violating her probation by showing up at O’Hare Airport without a plane ticket.

Hartman has been jailed since she was arrested last month for allegedly attempting to get past a Transportation Security Administration checkpoint at O’Hare — a violation of her probation for a 2018 conviction for sneaking aboard a flight from Chicago to London.

Before entering her guilty plea in last year’s case, Hartman spent months in a state mental health facility after being found unfit to stand trial.

At the request of Hartman’s lawyer, Judge Peggy Chiampas Monday ordered Hartman be evaluated for both fitness to stand trial and a possible insanity defense.

Hartman had been living at A Safe Haven, a residential mental health facility, after her release from the state mental institution.

It was not clear where Hartman was living at the time of her arrest in October, but Chiampas said she was concerned that Hartman might have moved out of A Safe Haven without notifying her probation officer.

In court, a probation officer read a report in which Hartman said that she wanted to move out of A Safe Haven, complaining that her roommates were substance abusers. She offered to pay for her own hotel room, the report said.

Chiampas said Hartman would remain at the jail pending her evaluation.

“She’s not staying at a hotel,” Chiampas said.

Over a nearly two-decade span, Hartman racked up numerous arrests for boarding airplanes without a ticket or trespassing at airports across the country.

Airport security officers carry a photograph of the silver-haired Hartman “at all times,” a prosecutor said at a hearing last month.