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

Dr. Thomas Barth said he observed Magnotta daily for about one week, beginning June 11, 2012, when he was transferred to his facility in Berlin after being arrested.

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

Often, he spoke about himself as if he were talking about someone else, Barth said.

The arrest warrant for Magnotta noted he had schizophrenia. Barth said his own diagnosis was that the accused 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.

The German doctor said he'd expected to have Magnotta under his care longer but that the extradition process went surprisingly quick. Magnotta was considered a "VIP patient" given the media scrutiny, his status as a foreigner and the seriousness of the case.

Magnotta never spoke about killing Chinese student Jun Lin in Montreal in late May and the doctor never asked.

"It's a very, very disturbing situation, even for a sane person," Barth said. "That's why I was very gentle with Mr. Magnotta"

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 and to ex-boyfriends who were cruel to him. He 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 an ex-boyfriend named Manny. He claimed the 35-year-old American was a pimp who allegedly forced him 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 Lin 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. Although Barth saw him daily, the native of Scarborough, Ont., spent much of his time in his cell.

Magnotta was upset after receiving what Barth described as "fan mail" in the form of postcards and letters. One letter asked him to wear a pair of socks he'd been sent and to mail them back.

During his stay, Barth said Magnotta was disappointed when he tried to contact his grandmother in Ontario only to have her hang up on him.

Defence attorney Luc Leclair asked Barth about sexual sadism -- the feeling of sexual pleasure from administering pain. Barth said it would take six months to make a proper diagnosis.

He was then given certain facts of the Magnotta criminal case and asked his opinion.

Barth said he might consider sexual sadism in Magnotta's case but, given a lack of previous evidence, his first instinct would be to look at schizophrenia.

"Sometimes in dealing with suspects from schizophrenia, you can't explain why something turned out to be violent and ended up a cruel offence," he said, declining to go any further because it would be unprofessional to make a diagnosis based on limited information.

Under cross-examination by prosecutor Louis Bouthillier, Barth repeated he never asked Magnotta about his alleged crimes and only briefly looked at the evidence himself.

"That was not my intention, to assess Mr. Magnotta," Barth said. "I was not involved as a forensic witness in this case."

And looking at the evidence "doesn't influence my testifying, which is confined to that week I saw and treated Mr. Magnotta."

Barth said, in his experience, some accused have faked psychosis in an attempt to get transferred from a dreary prison to his psychiatric facility, which he described as a "five-star hotel" in comparison.

It's possible to do so but it's a ruse that's difficult to maintain.

"If you're a good actor...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.