Instead, defence lawyer Luc Leclair ended his case focusing on the testimony of two psychiatrists who told the trial that Magnotta was in a psychotic state the night of the killing in May 2012.
They also said Magnotta had not been on medication for schizophrenia since 2010 and simply could not tell right from wrong.
While Magnotta maintained his right to silence, Leclair presented a dozen witnesses over roughly two weeks.
Magnotta, 32, is charged with first-degree murder in the slaying and dismemberment of Lin, a Chinese engineering student. The accused has admitted to the killing but has pleaded not guilty by way of mental disorder.
The key witnesses included Magnotta's biological father, who testified he too suffers from paranoid schizophrenia and began to see similar traits in his son during his late adolescence.
Forensic psychiatrists Joel Watts and Marie-Frederique Allard both assessed Magnotta and said he could not be held criminally responsible for Lin's death.
In the ninth week of the trial, prosecutor Louis Bouthillier began to present rebuttal evidence aimed at poking holes in the psychosis theory. The prosecution has argued Lin's death and dismemberment were planned and deliberate.
One witness — the last doctor to see Magnotta before Lin's slaying — testified he observed no signs or symptoms of schizophrenia or prolonged psychosis during an hour-long meeting on April 17, 2012.
Dr. Joel Paris, a Montreal psychiatrist, said he diagnosed the accused as having borderline personality disorder, which he said accurately depicted what Magnotta described: unstable moods marked by highs and lows, strained relationships and compulsive behaviour.
At one point during the consultation, Magnotta removed a wig he was wearing to show him he'd been ripping out his hair. Paris said Magnotta was anxious and was worried about getting fat.
Paris never saw the accused's voluminous medical records and didn't see any outward signs of schizophrenia or bipolar disorder.
"We didn't have the evidence for it," Paris said. "In other words, there was no evidence of an extended period of psychosis or chronic psychosis ... we didn't think that either of these were justified by the data we had."
The diagnosis was based on Magnotta's own answers. During the session, the accused did not ask for specific medications, didn't tell Paris or the resident with him that he was hearing voices and didn't reveal anything about a diagnosis of paranoid schizophrenic from roughly a decade earlier in Ontario.
The native of Scarborough, Ont., cast his previous mental health problems as bipolar disorder instead of schizophrenia and said the "noises" he'd heard were fuelled by cocaine use.
Leclair suggested that Paris purposely did not look for signs of schizophrenia because borderline personality disorder is the doctor's area of expertise.
Paris said he was missing information and that any conclusion based on partial information was not a firm one.
"All diagnoses after a single interview are bound to be tentative to a certain extent," Paris said.
Magnotta faces four other charges: criminally harassing Prime Minister Stephen Harper and other members of Parliament; mailing obscene and indecent material; committing an indignity to a body; and publishing obscene materials.
The Crown contends the killing was both planned and deliberate and presented four rebuttal witnesses, including Paris.
Two police officers testified about 2012 text messages seized from Magnotta's cellphone which outlined a drug transaction using street drug slang. Magnotta has told various psychiatrists he took drugs sparingly.
Later, the jury heard briefly from Dr. Gilles Chamberland, a forensic psychiatrist hired by the Crown to assess Magnotta.
Chamberland said he began sitting in on the trial once the defence started. He had access to medical records and Crown evidence.
The one hitch was that Chamberland was told Magnotta wouldn't meet with him.
Chamberland raised two possibilities based on the various versions of events Magnotta gave psychiatrists: that he suffers from either schizophrenia or more from personality disorder.
The second hypothesis is the easier explanation, Chamberland said, adding he finds it difficult that schizophrenia would be the root of all problems.
The Crown's expert didn't delve deeply into his nine-page report, but told the jury that one can be diagnosed with a mental illness and psychosis and not meet the criteria for a mental disorder defence outlined in the Criminal Code.
Like other psychiatrists in the proceedings, Chamberland called the case complicated.
"We could make an almost complete psychiatry course with what happened here," he said.
Chamberland returns to the stand Wednesday.
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