The boy appeared in court Friday in Montreal, the Montreal Gazette reported. A judge ordered him to remain in detention pending a bail hearing Tuesday.
The 16-year-old brother was shot Monday in his mother's home in Dorval, just outside Montreal. The 12-year-old was questioned during the night with one of his parents present at all times and then charged with manslaughter and possession of a prohibited gun, police said.
The funeral is scheduled for Thursday after a viewing Wednesday. Sonia Harvey, a legal aid lawyer representing the boy, said his parents want him there.
"It's absolutely necessary for them that he be present, to mourn together as a family," she said.
The parents have been divorced since 2008. In 2007, the father was charged with assaulting his wife and sons and with improper storage of weapons.
Harvey and another lawyer, Karine Doherty, said the boy needs a psychological evaluation.
"He's a 12-year-old boy who must be in shock," Doherty said. "He hasn't seen anyone in five days and under the circumstances, it's obvious he needs help."