Indian-origin psychiatrist Kabir Garg, 33, from Lewisham, south-east London, has pleaded guilty at Woolwich Crown Court to facilitating the exploitation of children.
National Crime Agency officers identified Garg as one of the moderators of a site called ‘The Annex’, which had around 90,000 members worldwide and saw hundreds of links to child abuse material shared every day.
Members accessed The Annex using Tor, a dark web browser which is estimated to have 1.4 million global users. Forty per cent of the total searches facilitated by Tor are for child sexual abuse material.
Officers arrested Garg at his flat in Lewisham in November 2022 as part of a coordinated operation with international partners, at a time when the site was open on his laptop with Garg logged into his moderator account.
His laptop and other devices were seized for analysis.
Until his arrest, Garg had been working as a psychiatrist for South London and Maudsley NHS Trust.
The Annex, which is no longer active, was run like a company and had a team of around 30 administrators, who worked in shifts around the clock to ensure the smooth running of the site.
Investigations showed that Garg was initially a member, but dedicated time and effort to becoming sufficiently trusted to be invited to be a moderator.
He was responsible for enforcing the rules of the site and removing members who did not comply. He also provided advice on how to evade law enforcement, shared and encouraged other users to share links to child abuse material.
Bethany Raine, specialist prosecutor of the Crown Prosecution Service's Organised Child Sexual Abuse Unit, said his crimes were "especially shocking given his role as a NHS psychiatrist, treating vulnerable members of the public, and his understanding of the psychological impact of sexual abuse on children."
She added: "When faced with the evidence of his crimes, Garg had no choice but to plead guilty."
The FBI has also arrested and convicted five men in the US for their involvement in running the site, one of whom has been sentenced to 28 years in prison.