A question of self-defense

The Washington Post has this article today about a 12-year old boy who killed a man attacking his mother. The article provides, in part:

The 12-year-old boy had finished his homework and was playing a video game when he heard his mother cry out. Rushing to her aid, he found her on the kitchen floor, straddled by a fellow resident of their Prince George’s County boarding house, the man’s hands wrapped tightly around her neck, the boy said yesterday.

“I kept saying, ‘Stop! Stop! Stop!’ ” the boy said, describing the events of Monday night. “But he just ignored me. He didn’t stop. He just kept hurting her.”

The boy said he grabbed a knife and swung, slashing 64-year-old Salomon Noubissie across the neck and opening an artery. Noubissie was fatally wounded.

The case presents exceedingly unusual circumstances: Rarely is a 12-year-old implicated in a homicide, and even less often does a child that age take a life to protect his mother.

“In Maryland, there can be a legitimate defense of third parties in the event of a violent attack,” State’s Attorney Glenn F. Ivey said. “That is a possibility in this case.”