Nearly four years after a deadly shooting in Montreal, the trial for the man accused of murder on election night 2012 is now underway.

Justice Guy Cournoyer began the trial on Thursday by warning the 12 jurors and two alternates that during the proceedings, and afterward, they must not discuss the evidence in any way, be it in personal conversations, via text message, or on Facebook.

He said that the accused, Richard Henry Bain, had elected to have the trial conducted in English but that many of the witnesses would testify in French, and that interpretation would be provided.

Bain has pleaded not guilty to six charges of murder, attempted murder, and unlawful possession of a firearm.

He is accused of killing Denis Blanchette outside the Metropolis nightclub in September 2012 as newly-elected premier Pauline Marois was delivering her victory speech.

Bain is also accused of shooting fellow technician Dave Courage.

Bain, wearing a white dress shirt and a neck brace, sat calmly while the judge read his instructions.

Crown prosecutor Dennis Galiatsatos then presented his opening arguments, explaining that the prosecution will prove Bain came to the theatre ready to kill with a semi-automatic rifle that he had equipped with an illegally large magazine of bullets.

He said Bain's plan originated over anger at being unable to vote in the provincial election after not registering a change in address.

Galiatsatos also pointed out that the men who were shot were not members of any political party.

He then called his first witness, Sureté du Quebec investigator Guillaume Vezeau, who oversaw the investigation.

Vezeau explained how he was at home the night of the murder, and was called and told to turn on his TV to watch the events unfolding.

He also said how the investigation determined where Bain was standing when he opened fire, how he poured gasoline in a stairwell, and set the building on fire.

Bain's lawyer, Alan Guttman, reserved the right to make an opening statement later in the trial.

The case has been repeatedly delayed as Bain rejected several lawyers, had problems paying for his defence, and most recently by Bain needing surgery.

The trial is expected to last six to eight weeks as the Crown calls 50 witnesses.