Christopher Husbands, 23, was led into a small courtroom packed with reporters, where new charges were read against him.
Police amended the charges against Husbands after the death of a second victim on Monday.
Husbands is now charged with two counts of first-degree murder, five counts of attempted murder and one of criminal negligence causing bodily harm.
He was previously charged with attempted murder in connection with the wounding of 22-year-old Nixon Nirmalendran, of Toronto, who died Monday.
Nirmalendran was among six people wounded in the June 2 shooting which took place in the food court of the multi-level shopping mall. The incident also killed Ahmed Hassan, 24, who died of gunshot wounds at the scene.
Nirmalendran had not been identified in previous news reports because of a court-ordered publication ban on the identification of victims and witnesses to the shootings. However, the ban does not apply to deceased victims.
Police have said their investigation suggests the shooting was a targeted one.
Officials had said earlier that Husbands, Hassan and Nirmalendran all belonged to the same gang.
But police have also said they believe the shooting was the result of a personal dispute and was not gang-motivated.
Husbands was under house arrest for a previous charge at the time of the shootings, police said.
The incident sparked mass panic at the centre packed with shoppers and a widespread manhunt for the shooter. Husbands turned himself in to police two days later.
Investigators are still asking anyone with information on the shooting who hasn't already contacted police to do so.
(CFRB, The Canadian Press)
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