MONTREAL -- Jurors at Luka Rocco Magnotta's murder trial will be working on the weekend after failing to reach a verdict on Friday, their fourth day of deliberations.

Magnotta is charged with first-degree murder and four other charges in the slaying and dismemberment of Chinese engineering student Jun Lin in May 2012.

Late in the afternoon Friday, the jurors sent a note to the judge advising him they weren't able to watch certain videos on the court-issued computer in the room where they are deliberating.

Quebec Superior Court Justice Guy Cournoyer asked a constable to retrieve it so a technician could have a look. The judge and lawyers agreed not to ask the jury if they were still deliberating.

The eight women and four men began their work on Tuesday and have emerged just once over the four days.

That was on Wednesday when they asked the judge whether a personality disorder is a disease of the mind from a legal standpoint. Cournoyer told them it was.

Magnotta has pleaded not guilty by way of mental disorder and is seeking to be found not criminally responsible. His lawyer says he is schizophrenic and couldn't tell right from wrong at the time of the slaying.

Prosecutor Louis Bouthillier has argued the schizophrenia was a misdiagnosis and that his medical problems and behaviour are likely the result of personality disorders.

On the murder charge, the jury has four options: find Magnotta guilty of first-degree murder, second-degree murder or manslaughter, or find him not criminally responsible because of mental disorder.

The judge told the jurors Monday that if they find the accused not criminally responsible, that verdict must be the same for all five charges.

Besides the murder charge, Magnotta is also charged with 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.