It all relies on two things; Justification and rehabilitation.
Justification is simple, here stands a convicted rapist, a murderer and a child molester. We know they do it, maybe they've been convicted of the crime, maybe we know they have been let off on mere technicalities, whatever. People can justify the act of retribution against them, maybe kill them, maybe rape them back, an eye for an eye. Or maybe it's simply a case of stealing or causing damage to their operation or daily life in order to make it harder for them to commit their crimes. Whatever the case, you'll never get a consensus, but you very well may get a group of people leaning towards a particular cause of action or witch-hunt.
But your query is far too wide. A known criminal? Of what? Do we go as far to justify committing civil offences against those who trespass? Do we go as far to justify committing crimes against those who maybe did something silly when they were drunk? For example, a person who punched a window in order not to take his anger out on another human being, who subsequently turned himself in and was convicted but let go as a redeemable person who committed a (hopefully) one off offence? His crime? Minor Criminal Damage. Does he thus become a justified target for 'criminal activity'?
And what of those who are committing the 'crime' against those known criminals? Do they automatically become eligible to be attacked tit for tat, because even if something is 'acceptable' it doesn't mean that it isn't any more a crime than what the original offenders did in the first place. You'll end up with a world of 'criminals', whether known or otherwise.