A psychiatrist who met with alleged murderer Richard Henry Bain nearly two weeks after his arrest in 2012 says it's clear to her he was in a manic state brought on by bipolar disorder.

Marie-Frederique Allard took the stand Wednesday for the defence at Bain's first-degree murder trial.

Bain has pleaded not guilty to the murder charge, three counts of attempted murder and two arson-related charges in connection with a shooting on Sept. 4, 2012, the night the Parti Quebecois won the provincial election.

Lighting technician Denis Blanchette was killed and fellow stagehand David Courage seriously injured after they were both struck by the same bullet outside the club where the PQ was celebrating its victory.

The Crown has argued the crime was premeditated and politically motivated, while the defence has countered Bain should be held not criminally responsible by way of mental disorder.

Allard, a forensic psychiatrist, said Bain's then-lawyer asked her to meet with the accused at a detention centre on Sept. 18, 2012, to evaluate his mental state.

"He was clearly psychotic with symptoms of mania," she told the jury of her first visit.

Allard called that meeting "difficult" as Bain was at times irritable, angry and arrogant.

He wouldn't speak much about the night of the shooting, mostly referring to dissatisfaction with his attorney, complaining about his detention conditions and alleging he was the victim of persecution.

Allard said he also didn't seem particularly preoccupied by the fact he was facing the most serious charge in the Criminal Code.

She testified he told her he was doing God's work.

"Whatever I'm doing is sanctioned by him," Allard quoted Bain as telling her before he reportedly said, "my God will judge me."

Allard testified it was clear to her following the three-hour session that Bain was psychotic but that it was impossible to say how long he'd been in a manic state.

She said it's not uncommon for a manic episode to last many weeks or months.

"I didn't know when the episode started, but I knew on the 18th, Mr. Bain was experiencing psychosis and this psychosis was related to bipolar disorder," she said.

The following day, Allard called Bain's treating psychiatrist to take him off his anti-depressant medication, which tends to induce such manic episodes.

That was the day Bain called radio station CJAD from jail and gave a 38-minute interview outlining his political vision for Montreal to split from Quebec.