I would definitely want to see them prosecuted. However, the sentence should probably be light. I’m not perfectly familiar with the justice system, so I don’t know how much of this is currently the case, but I think vigilante justice should result in smaller punishments than for example if the reason of the murder was personal gain. If it can actually be proven that the murder victim did those terrible things they were killed for, depending how terrible those things are, the sentence should be reduced. If for example someone killed Hitler, there should be no punishments for this person.