Salth was right, and Matt's not kidding here; Stephanie was, in fact, the first person he has ever been forced to actually kill, a fact of which Matt is not proud at all. Even besides the basic sanctity of life in general, thieves make it a point to avoid killing anyone at all. Not only is it a mark of sloppiness that they were unable to either avoid detection or escape once found, any decent thief understands that dead bodies tend to attract plenty of attention. Regardless of whether or not anyone saw the killer strike, that sort of thing tends to put people a bit on edge. This is sort of counterproductive to someone attempting to sneak away.

So the lesson here is that dead men do, in fact, tell tales, and frequently louder than any living man possibly could.