"Across the Pond" (as the British like to say), there is a very similar problem with vigilantes. According to this brief article, many vigilantes commit crimes during their vigilante actions, and vigilante groups attract domestic abusers and others with a lack of volitionakl control. Much of that behavior can be seen in the people profiled here over the years.
https://www.theweek.co.uk/104198/why-police-are-worried-about-increase-in-paedophile-hunters
UK police have voiced major concerns about the activities of socalled paedophile hunters who attempt to entrap potential child sex offenders without the help of authorities.
According to the BBC, such vigiliante groups often contain members who set up fake profiles on social media, purportedly belonging to teenagers, and wait for adults to contact them.
The broadcaster says that once contact has been made they will then “confront the suspect, usually filming the operation, before handing their evidence to the police”.
This week Dan Vajzovic, of the National Police Chiefs' Council, warned against this form of activism. He claimed hunters “often divert police resources away from other offenders and often commit offences themselves during their operations”, including “extortion, blackmail and exhibiting violence against those that they are targeting”.
According to ITV News, some police “fear that the groups’ actions could interfere with surveillance operations, while the evidence they gather may not be of a high enough standard to use for prosecution” anyway.
Former police chief Jim Gamble told the Independent Inquiry into Child Sexual Abuse in early 2018 that “masquerading as a child online should become a criminal offence to deter vigilante stings”. He also told The Telegraph this summer that such groups “attract people with domestic abuse records and coercive control. They give people the opportunity to reinvent themselves as a good person and create this status, to build a Facebook or a Twitter following.”
The National Society for the Prevention of Cruelty to Children (NSPCC) said that while it had “sympathy” for those who target suspected abusers, protecting children was its “ultimate priority”.
“If someone has concerns about child safety the best way they can help is to alert the police,” the society warned.
But Paddy Tipping, the police and crime commissioner for Nottinghamshire, said in April last year that police in his area should try to form “better relationships” with vigilante groups. A recent freedom of information request filed by the BBC has shown that last year prosecutors used evidence by so-called paedophile hunters in more than 250 cases against suspected abusers.