Jim Gamble, the former head of the Child Exploitation and Online Protection Centre (Ceop), said he understood “the frustration” that drove Stinson Hunter to target suspected internet predators.
A new documentary shows the 31-year-old former drug addict, who said he witnessed child abuse while he was in care, posing online as an under-age child and being approached by men sending explicit messages, videos and pictures and arranging to meet up.
They are then lured to a house where they are confronted, filmed with handheld cameras and mobile phones, and asked to explain themselves before Hunter hands the evidence to the police and publishes it on his website.
Mr Gamble said: “Some people with very little training are proving just how easy it is to go out there and catch individuals. They are able to go online with little or no training and very quickly they’re shooting fish in a barrel.
“The fact of the matter is this, that needs to be done by law enforcement and whilst I don’t see any justification in reality for vigilantes doing what they do I think it provides the evidence for the Government, if it’s needed, that actually this works.”
Hunter has filmed confrontations with dozens of men including soldiers, teachers and solicitors and seen his evidence help in 10 convictions.
Mr Gamble said his actions created “a risk” to himself and other people and one man, Michael Parkes, 45, killed himself last year after being questioned by police after he was confronted and footage uploaded to the internet.
Mr Parkes’ partner, who was also interviewed for the Channel 4 documentary, said she “may agree” with Hunter going online to gather evidence but said publishing the videos was “what probably tipped him over the edge”.
Hunter told film-maker Dan Reed: “We set the profile. It’s like a rope and if they choose to put the rope around their neck and hang themselves that’s their choice. We’ve not pushed them.”
The film, called The Paedophile Hunter, is being screened on Wednesday at 10pm on Channel 4.