A talented scientist exposed as a prolific online paedophile blackmailed one of his young victims into licking toilet seats and eating dog food, a court heard.
During a secret double life during years of study at Cambridge University, Dr Matthew Falder made children, young men and women photograph themselves in compromising positions and shared the material with other abusers interested in so-called "hurtcore", which depicts rape and abuse.
The 29-year-old geophysicist pleaded guilty to 137 charges relating to 48 people at Birmingham Crown Court in October.
He is to be sentenced this week, with prosecutors telling the court how he targeted vulnerable people, including anorexic teenagers, by posing on the internet as a depressed female artist offering them money for images.
He contacted hundreds of victims through marketplace websites such as Gumtree and would blackmail them with a "constant stream" of increasingly depraved requests, with one young girl forced to lick a used tampon and record herself holding racist and homophobic signs.
Falder told one victim that if they did not send him more material, he would "send the images to everyone on Facebook associated with your school, and in letters to your parents and teachers, explaining with printouts of all the pictures that you will strip for money".
Another youth was encouraged to rape a four-year-old boy, while others were sent naked photos of previous victims - which Falder pretended were him to gain their trust.
Opening the three-day sentencing hearing on Wednesday, Ruona Iguyovwe, from the Crown Prosecution Service, said Falder, of Edgbaston, enticed his targets to produce "increasingly severe self-generated indecent images of themselves", which she said were designed to "humiliate and degrade" them.
Falder, who hid behind pseudonyms such as "666devil" and "evilmind" and used anonymous email accounts, was said to be "unmoved" by his actions, which led to three of his victims attempting suicide.
Some threatened him by saying they would call the police, to which he bragged: "I can't be caught."
Describing the impact of his actions, one of his victims told the court: "I feel dirty, like used goods. Part of me believes that's all I am good for anymore - to be abused."
In an emotional statement, she added that the abuse had led to the breakdown of relationships with her parents and boyfriend, forcing her to leave home.
Falder, who grew up in a wealthy part of Cheshire, committed his crimes for more than eight years before he was unmasked by the National Crime Agency in 2017.
He was arrested at Birmingham University, where he worked as a post-doctoral researcher.
The NCA had help from GCHQ, the FBI, and law enforcement in Israel, Slovenia, Australia and New Zealand.
The sentencing hearing is scheduled to end on Friday, and Falder is expected to be given a long jail term.