Self-defense, then. [Shame it wasn't murder, but then again, a murder discovered would have been disappointing in its own right. Perhaps it was better that his hand was forced.]

He's most experienced with those guns everyone's so fond of, but he had a little training with knives. I decided to supplement that.

Oh, I'd recommend not attempting concerted outreach to him, by the way. One would risk the impression of attempting to replace his departed father.