A Melbourne boy acted bravely and protectively when he shot and killed a man who was beating his mother, a coroner says.
The boy picked up a gun that Ayhan Paul Ferman dropped as he threw the boy's mother through a sliding door, and fired a shot into Mr Ferman's chest.
State Coroner Ian Gray said the 12-year-old, who cannot be named, was defending his mother and commended his actions.
"(He) is entitled to be told that the court recognises that his action, in the heat of the moment, was quick thinking, brave and legally justified," Mr Gray said on Wednesday.
"His mother was clearly the subject of a serious assault by Mr Ferman before (he) shot at him."
Mr Gray noted the boy was visibly upset when told by police he had killed Mr Ferman, asking "has he got children - they will no longer have a father".
Mr Ferman bashed at the door of the Coburg home the boy shared with his mother and intellectually disabled brother around midnight on May 22, 2010.
He demanded to see the boy's mother and was allowed inside, where he began to verbally abuse her, claiming she had disrespected him.
Mr Ferman then spat in her face, threw her through the door and began kicking her on the ground.
After trying to pull Mr Ferman off his mother, the boy then picked up the gun and fired.
Judge Gray said before emergency crews arrived at the home an unidentified man came to the door to ask if Mr Ferman was OK.
Once told he had been shot, the man took the gun and fled.
The Office of Public Prosecutions did not charge the boy, finding the "evidence discloses a viable defence of self-defence", Judge Gray said.