This isn't NYC in the 1970s when you could get away with that. If people started doing that today, the state would bring their swat team down on the vigilante, take all of his shit, and then charge him with murder. Because those poor criminals that died were oppressed and they need compensation. And then they'd charge him with possession of child pornography, which they "found" (planted) on his computer, to distract from the vigilante charges.
The state wants no competition when it comes to the crimes they commit. The people are subjects, not citizens.