The man, Stephen King, a resident of South London, pleaded guilty to 21 counts of sexually abusing three young girls over a period of three years while he worked with police and criminal prosecutors on establishing proper criminal sentencing for pedophiles. One of the victims was as young as ten years old.
King also organized conferences on child protection and he claimed to be an expert on the Children's Act and pornographic pictures of children.
King was sentenced to seven years in jail.
The prosecution said that King had taken more than 500 indecent photographs of his victims and kept a video showing acts of indecency with the girls. He also kept a journal of each sexual encounter, prosecutors said.
"Stephen King in my view is a devious, predatory pedophile who has preyed upon young children in this country for somewhat over three decades," a detective involved in the case said.
According to reports, the sexual assaults took place between October 1996 and 1999 when the victims were between the ages of nine and 13.
Police officers first stumbled on the case when they went to King's house on suspicion of benefit fraud. According to reports, while conducting a search, they discovered incriminating child pornography material and alerted Scotland Yard's Pedophile Unit.
"It was depraved, corrupt and persistent behavior on vulnerable young girls," Judge Fabyan Evans said at the time of King's sentencing. "You took advantage of three of them, one with learning difficulties."
There is speculation on behalf of investigators that there are other children out there who have been abused by King, but who haven't stepped forward yet.