What this man failed to understand is that the police, the prosecutors the mayor and city leadership and the police union all look bad when this guy succeeds. They do not want any competition as they have a monopoly on the business of law enforcement so therefore they will prosecute him in order to stop him. Even though he did this out of the goodness of his heart, APD and the rest of the law enforcement game see him as a threat to their job security. When private citizens can police the city better than government bureaucracies people start to question why we pay and hire police who cannot do the job, public funding becomes uncertain and people in the government monopoly start getting scared. This has nothing to do with preventing 'vigilanteism' and everything to do with the government bureaucratic monopoly saving face from the mere whiff of private competition.