I dont know for sure if this guy was really jogging, or if he was casing something out to steal. It could have been either. What is certain though is that those three guys screwed up. We do not operate on mob rule and that needs to be consistent wether it's rulings by a court of law or people on the street.
I dont know what those guys were thinking but, it's not a citizens job to go after someone with guns, based on a suspicion. They would have had to actually see him being a threat. They had a truck and could drive faster than anywhere he could run. All they needed to do was follow at a distance and call the police to question him. This is the kind of thing that can happen when people try to take the law into their own hands, now one person is dead and three are likely going to prison.
On a side note however, we can expect more of this if police officers continue to quit their jobs and begin to back off from proactive policing. At some point more people will be reverting to defending themselves more aggressively.