Careeer criminals are usually pretty good about getting away with crimes, because they KNOW it's bad, they know the police will try to arrest them.

Teens who are white-knighting for justice, not so much. They believe that they are doing the Lord's work, so they do stuff like shoot guys in the head in a parking lot with witnesses standing around.

A dedicated bad guy would have sniped the hobo from the trees, probably while he was homelessing under a tarp.