MONTREAL - The trial for a man accused of committing murder during a home invasion began in a Montreal courtroom Tuesday.

Denis Therrien, 30, is accused of killing Robert Brassard, 59, on May 1, 2010, when Brassard tried to fight off his attacker.

Therrien allegedly entered Brassard's apartment on Bourbonniere St. in the Hochelaga-Maisonneuve district at 6 a.m., while Brassard was asleep.

The suspect is alleged to have hit his 70-year-old sister Noella on the head, knocking her unconscious, and then attacked Brassard, stabbing him the head head at least 15 times. He died of his injuries later in the day.

Police had no leads until a man named Sylvain Savard contacted them six months later with information about the crime.

Savard, a friend of Therrien's, told police that the suspect confessed the crime in a private conversation.

Savard brought police to a gutter where they located a screwdriver allegedly used in the home invasion.

Investigators also found a weight from a barbell, which they believe the alleged killer found in the apartment, and used to attack the victim.

Prosecutors plan to prove the weight was also used on the victim's sister, who is expected to take the stand.

However one key piece of evidence was needed to prove that Therrien was actually in the Bourbonniere St. home, and police believe they have that evidence in the form of a single drop of blood.

A DNA test on the blood drop indicates it came from Therrien.

Therrien has pleaded not guilty.