The Crown prosecutor said enough evidence was gathered to indicate the incident was not accidental.
"For now, we have enough evidence to lay these charges," said Crown prosecutor Marie-Claude Bourassa. "Let's remind ourselves that he is a 12-year-old. We're not trying to make a point. This is a very sad case, but the evidence is sufficient to lay these charges."
The boy entered a plea of not guilty today in youth court.
He could face a maximum sentence of three years in a youth detention centre. The charges will be dealt with in youth court because of the age of the accused.
The 12-year-old will appear in court for a bail hearing on Jan. 25.
Bourassa said the boy will remain at a youth detention centre for the time being.
Teen shot dead in family home
The 16-year-old boy died yesterday after being shot in the head at his family's home in Dorval.
Montreal police Const. Simon Delorme said major crimes unit investigators interviewed his 12-year-old brother through the night until about 5:30 a.m. ET today.
Delorme said this is a difficult case, given the boy's age and the strong emotions involved. Investigators with the major crimes unit were still at the house this morning.
The boys were alone in their house at the time of the incident.
A spokesperson for paramedics with Urgences-Santé said it appears the two boys were playing with a gun.
Police said the handgun belonged to the family.
Because they are still speaking with witnesses, police said they could not specify if the gun was registered or how it was stored.
Victim's brother calls 911
Police were called to the family's home on Hamilton Place near Thorncrest Avenue in Dorval, at about 5:30 p.m. on Monday.
Ambulance officials said the 12-year-old called 911 to report the incident.
The boys' mother returned to the home after emergency personnel were already on the scene. She was taken to hospital to be treated for shock.
The 16-year-old victim was a student at Lakeside Academy in Lachine, Que.
A spokesperson at the school board said trauma counsellors are at the school today to speak with students.