A teacher who manipulated people around the world to sexually abuse children in their care was branded a "malign puppet master" by a judge as he was jailed.
Richard Clark used a series of false identities in order to "manipulate" victims into committing sexual abuse on children, recording the content for his own satisfaction.
In some cases, he was able to convince web-users to send images and recordings of their own relatives, and in one instance the person being photographed was so young that a nappy could be seen.
York Crown Court heard how the 29-year-old also used fake social media accounts in order to pose as a teenager, often pretending to be friends with victims and asking that they send indecent photographs of themselves, sometimes in return for images that he had downloaded from the internet.
In many cases, this would be done via Snapchat, after which Clark would secretly take screenshots of the images without the sender knowing.
The teacher, of Topcliffe Road, Thirsk, North Yorkshire, also kept a record of his victims, categorising them based on their appearance, the size of their genitalia and the ways that he had abused them.
The court heard how his offending, which impacted upon victims across the world, led to the issuing of 79 Child Exploitation and Online Protection (CEOP) packages being issued both in the UK and internationally, with 17 children having to be either removed from their homes or safeguarded.
Clark admitted to 26 separate charges and a further 54 offences were taken into consideration during his sentencing on Tuesday.
Jailing him for 12 years, with a further eight years to be served on licence, Judge Andrew Stubbs QC told him: "You are an educated and intelligent man, and you used that intelligence in order to create a web of false identities to offend both here and around the world.
"It is plain that this was all done for your own sexual gratification. You manipulated others to abuse children at your discretion like some sort of malign puppet master."
The judge added that Clark had rated his victims "as objects" for his own satisfaction, saying that many felt "trapped" as he accrued sensitive images of them.
The court heard how one said they were contemplating suicide in order to escape the defendant.
The judge added: "You systematically robbed your victims of their character, their self-esteem and their life chances."
The offences spanned between April 2016 and April 2018, ending when he was arrested by officers from North Yorkshire Police.
In total, Clark admitted to ten counts of arranging or facilitating the commission of a child sex offence, three of distributing indecent photographs of a child, nine of causing or inciting a child to engage in sexual activity or send indecent images, three of possession of indecent photographs of a child and one of possession of an extreme pornographic image.
After the sentencing, Detective Chief Inspector Jim Glass, of North Yorkshire Police, said: "This has been an extremely complex and challenging case, throughout which the identification and safeguarding of Richard Clark's victims has been a priority.
"Working with a number of partners including the Children's Safeguarding Board, North Yorkshire County Council, Health and Social Care and the Crown Prosecution Service, we have ensured the best possible support for all those affected throughout this case.
"The inquiry continues to send out intelligence to other police forces and law enforcement agencies around the world in relation to additional victims and offenders' details which have been identified."