Tobby Carrier of Matane is accused of stabbing his brother to death after a violent altercation with his parents on March 31, 2009.
During opening statements in court, the 10 men and two women on the jury listened as the Crown alleged Carrier had been planning to kill his family members since he was 12 or 13.
Crown prosecutor Guy Loiselle said Carrier's parents were packing their bags to go on a trip when he attacked them. He was 19 years old at the time.
Loiselle said Carrier had been on the internet chatting with a friend before putting on a hooded sweater.
He entered the bathroom where his mother was and tried to strangle and stab her several times, he said.
Upon hearing his wife's screams, Carrier's father came to her defence, but Loiselle said Carrier stabbed him as well.
Loiselle said Carrier then stabbed his older brother, Ismaël, 21, who was downstairs.
Both parents spent a week in hospital, but the brother didn't survive the attack.
Court procedures were delayed several times because of psychiatric evaluations requested by the defence and the prosecution.