MONTREAL - The Crown's expert witness at Luka Rocco Magnotta's murder trial is telling the jury why he believes the accused was suffering from personality disorders when he killed Jun Lin.

Psychiatrist Gilles Chamberland says Magnotta tends to exhibit elements of borderline, histrionic and narcissistic personality disorders.

Chamberland testified Monday that those conditions are a more reasonable explanation than schizophrenia for his behaviour.

Magnotta is charged with first-degree murder in Lin's slaying in May 2012.

He has admitted to committing the acts but has pleaded not guilty by way of mental disorder.

Defence psychiatrists have testified they believe Magnotta was psychotic, had been untreated for schizophrenia for at least two years and was unable to tell right from wrong the night Lin was killed.