A Cambridge University graduate is facing years in jail for blackmailing more than 50 people into sending him abusive images of themselves and children - before spreading them on the internet.
Dr Matthew Falder, 28, pleaded guilty to over 100 charges including sharing degrading images on the dark web.
The geophysicist, who was employed at the University of Birmingham, humiliated his victims under the name "666devil" and "evilmind".
Posing as a female on sites such as Gumtree, Falder would trick targets into sending him naked or partially naked photos before blackmailing them into sending even more abusive images.
On Monday at Birmingham Crown Court, he admitted causing child sexual exploitation, voyeurism, making and distributing indecent images of children and encouraging the rape of a four-year-old.
For more than six years Falder targeted dozens of victims, including men and women.
Among pictures Falder shared on the dark web were ones of babies and children being tortured - images he then discussed at length.
The academic was arrested on June 21 this year and had been held in custody since.
Flader's case is the National Crime Agency's (NCA) first in "hurt core" offending - the hidden web forums dedicated to the discussion of and video sharing of "dark" material.
The offender was branded "highly manipulative" by the Crown Prosecution Service and a "truly evil offender" by the NCA.
Matt Sutton, a senior investigating officer, said: "In 30 years of law enforcement I have never come across such horrifying offending where the offender's sole aim was to cause such pain and distress."
And in a rare statement, GCHQ said it was "proud" to have assisted the NCA investigation.
A spokesperson said: "Working to counter this kind of terrible child sexual exploitation is an important part of our mission to help keep the UK safe online and protect the digital homeland."
Falder, of Edgbaston, Birmingham, will be sentenced on December 7.