A Falmouth man accused of murdering his mother at their home last year was scheduled to change his plea to guilty on Tuesday, but before the court hearing could begin a judge ordered him to undergo an emergency mental health evaluation.

Although Andrew Leighton, 48, was in custody in the Cumberland County Courthouse in Portland for the scheduled hearing, he was never brought into the courtroom.

Leighton’s attorneys, Robert LeBrasseur and Scott Houde, met with him in private, then returned to the courtroom to whisper with Assistant Attorney General Leane Zainea, who is prosecuting the case against Leighton. The lawyers then left the courtroom again to speak with Superior Court Justice Thomas Warren behind closed doors.

Leighton’s attorneys would not say what happened during their talk with their client, but confirmed that the judge saw fit to have Leighton evaluated by a forensic psychologist to assess his mental state.

“We were unable to proceed,” LeBrasseur said, declining to comment further on his client’s behavior.

Leighton had previously pleaded not guilty by reason of insanity to a single count of murder in the May 3, 2013, shooting death of his mother, Shirley Leighton of Falmouth.

Before attorneys reached an apparent plea agreement for Leighton, he had been scheduled to stand trial for his mother’s death starting on Jan. 12. Now it is unclear whether the trial will start on that date.

“We’re trying to figure out when we’ll go forward, if we’ll go forward, with a change of plea or trial,” LeBrasseur said. “It depends on how the evaluation comes out.”

Zainea declined to comment on what happened behind closed doors after she returned to the courtroom to gather her belongings.

The attorneys also declined to comment on what terms they had reached on a plea agreement for Leighton.

Leighton is accused of shooting his mother just before she and his father, Thomas Leighton, were to have him committed for mental health treatment. Leighton had lived with them at their home on 19 Edgewater Road in Falmouth for about six years after a divorce, according to court records.

His father had left to take the dog for a walk before bringing Leighton to a psychiatric facility, Spring Harbor Hospital in Westbrook, and when he returned, Leighton told him he had shot his mother, the records show.

Leighton and his father initially struggled over a gun, a .40-caliber Baby Eagle, and his father ultimately escaped by running away. Leighton was arrested after a five-hour standoff with police.

Leighton has already undergone some mental evaluations since his arrest and was found competent last year to stand trial.

Depending on what a forensic psychologist finds in the emergency evaluation – which can be conducted at the Cumberland County Jail, where Leighton is being held – the judge could order a longer-term forensic evaluation.

This is the second time Leighton’s case has been scheduled for trial. Lawyers attempted to seat a jury on March 11, but went through a pool of 106 potential jurors without seating enough for the trial to begin. The case has faced scheduling delays since then.