Sorry, but you seem pretty quick to "assume" also ("maybe due to mental illness or being threatened or being bullied").
If someone robs a business that sells guns with a sledgehammer, maybe it's just because the robber didn't own a gun and grabbed the biggest weapon he had on hand. Or maybe it's because he's a bad shot and is more comfortable using a hammer. See, I can assume too, can't I? All that you have suggested is speculation; it's not based on facts. What you call "thinking outside the newslines" is what I call unfactual assumptions.
"If it were someone you knew that had never committed a crime and this was totally outside of their personality" - Well, this wasn't the case. He robbed the place before (without a weapon).
The point is that the robber caused his own death the minute he walked in the door with that hammer. Done.
More information about formatting options