In her report, Marie-Frederique Allard said she determined Magnotta was not criminally responsible in the death because he was schizophrenic and in a poor mental state after not having had proper psychiatric care since 2010.
Magnotta has admitted to killing Lin but is arguing he was suffering from a mental disorder. He faces one count of first-degree murder and four other charges in the slaying.
Allard has said Magnotta told her he believed Lin was a government agent sent to kill him and that voices urged him to "cut it" and to "give it back to the government."
In his cross-examination at Magnotta's murder trial Wednesday, Crown prosecutor Louis Bouthillier said the version of events the accused gave Allard raised several inconsistencies and unanswered questions.
Among them, according to Bouthillier:
— Why was Magnotta wearing Lin's hat hours after the Chinese student's slaying and dismemberment if he believed Lin was an agent? Was it kept as a trophy?
— If it was meant as a message to the government, why was the so-called murder video of Lin's gruesome death published on a gore website and not sent directly to the government?
— Why did Magnotta leave his apartment at 2 a.m. if he thought government officials spying on him were in a dark vehicle outside?
— Did he have an explanation for why he was brandishing an oscillating saw as he stood over a sleeping mystery man less than one week before Lin's slaying?
These and many other questions were met with similar responses from Allard — either she hadn't asked Magnotta or he hadn't offered a proper explanation.
Bouthillier called Magnotta a "pathological liar" who had an interest in telling half-truths to Allard to escape jail time.
The veteran prosecutor said the accused had already demonstrated that ability by admitting to Allard about fibbing to medical professionals in 2011 and one month before the 2012 crime.
"He lied to a psychiatrist to get out of being hospitalized," Bouthillier said. "He could also have lied to get out of going to prison."
Justice Guy Cournoyer issued an instruction after Bouthillier's repeated descriptions of the accused as a liar, reminding the jury that Magnotta benefited from the presumption of innocence.
Allard said Magnotta's schizophrenia medications, which he started taking regularly after his arrest in June 2012, could be responsible for his memory lapses.
She has done roughly 900 evaluations of different types over a 15-year career. Allard repeated Wednesday that Magnotta was challenging, that his responses were often scattered and that he couldn't remember details.
The Crown also said there were differences between the version Magnotta gave Allard and one he gave another psychiatrist who is scheduled to testify for the defence.
Bouthillier was able to grill Allard on several pieces of information she said she either found out about recently or failed to put into her 127-page assessment of Magnotta.
One example Bouthillier asked about that did not make it into Allard's report involved the suitcase into which Lin's torso was found stuffed. Allard said Magnotta remembered buying it but did not remember damaging it.
Bouthillier suggested the suitcase was intentionally slashed, smeared with paint bought at an art-supply store, and fitted with a lock to prevent a passerby from collecting it from the trash.
The prosecutor asked Allard if she was satisfied with Magnotta's responses. She said she was but added she wassn't surprised if he withheld certain things.
"I think when we meet patients, we'd like for them to recount exactly what happened," Allard said. "Sadly, for the most part in my line of work, that's not what happens."
Allard was also confronted with surveillance video from Magnotta's apartment that showed him acting calmly as he discarded the contents of his apartment. She replied it was unclear what was going on inside his head but agreed he looked calm.
Her cross-examination continues Thursday.
Follow (at)sidhartha_b on Twitter.
ALSO ON HUFFPOST: