MONTREAL -- A German psychiatrist who met with Luka Rocco Magnotta in 2012 at a Berlin prison hospital following his arrest says he believes the accused was suffering an episode linked to suspected paranoid schizophrenia.

Dr. Thomas Barth held daily meetings with Magnotta for about one week, beginning June 11, 2012, when he was transferred to his facility in Berlin.

Barth, testifying in person Tuesday as a defence witness at Magnotta's first-degree murder trial, said the accused rambled during their first session, offering bursts of information before quickly changing the subject.

The arrest warrant for Magnotta noted he suffered from schizophrenia. Barth said his own diagnosis was that Magnotta suffered a "severe psychotic episode related to suspected paranoid schizophrenia."

Barth labelled it as "suspected" because typically such an evaluation takes up to a month and that Magnotta was only at the facility for about one week before being returned to Canada on June 18, 2012.

Psychiatrists are very careful about diagnosing someone as schizophrenic, Barth noted, saying it is the most severe diagnosis for a patient in his field and one that can have a lasting impact.

At their first meeting, Magnotta told Barth he was hearing voices -- a key symptom of schizophrenia. Magnotta told him "he felt like he had a radio in his head."

Barth said Magnotta appeared shy as they spoke in the prison library. He talked about everything from fears of being watched, to family troubles, to ex-boyfriends who were cruel to him, and even discussed Prime Minister Stephen Harper.

"It came out of the blue, as with almost everything he presented," Barth said.

According to the German psychiatrist, Magnotta:

-- Said he had a 35-year-old American ex-boyfriend named Manny. He claimed he was a pimp who allegedly forced Magnotta to have sex with other men, beat him and forced him to make bestiality sex tapes.

-- Claimed he was being watched and filmed by a witch he eventually called Debbie. During his initial meeting, he asked Barth to close a window because she was watching.

-- Alleged another ex-boyfriend, named Robin, forced him to take steroids and tried to poison him.

-- And said he always felt handicapped, mentioned his father was a schizophrenic and added he hated his alcoholic mother.

Magnotta, 32, is charged in the slaying and dismemberment of Jun Lin in May 2012 in Montreal before he fled to Paris and then Berlin, where he was arrested.

He has admitted to killing the Chinese engineering student, but has pleaded not guilty by way of mental disorder.

Barth said Magnotta only mentioned he was hearing voices in Germany a day before being admitted to the psychiatric wing.

While there have been cases of patients faking psychosis as a way of getting away from prisons, Barth said it's a ruse that's difficult to maintain.

"If you're a good actor or if you're experienced with psychiatric patients, you can fake it," he added. "But I doubt you can fake it for a longer time."

Barth said no one in the German prison hospital had any doubt Magnotta was suffering from schizophrenia, noting that some staff appeared to express sympathy for him.

Magnotta faces four charges in addition to premeditated murder: criminally harassing Harper and other members of Parliament; mailing obscene and indecent material; committing an indignity to a body; and publishing obscene materials.