Never met a mugger in my life who would be ballsy enough to shoot someone & not take what he came for.
Muggers and robbers kill people all the time without getting away with any money or goods.
You and police have no idea what the attacker may have gotten just because his wallet was not taken. An apparent attempt was made to get his watch, and a leather watchband doesn’t tear without a good bit of direct violence.
Believe what you want but you have NO evidence this was a hit. The fact nothing was stolen isn’t evidence.