A computer expert who set up websites advising paedophiles about accessing child pornography has been jailed for three years.
Martin Jarvis (65) also downloaded more than 300,000 indecent pictures of children, and distributed around 20,000.
Leicester Crown Court was told that officers from the Child Exploitation and Online Protection Centre accessed a chat forum which led them to a website linked to the defendant.
Jarvis's former home, in St Bernards Road, Whitwick, was raided, and police seized his computer equipment.
Jarvis pleaded guilty to 12 counts of distributing child pornography during 2012, 11 counts of making indecent images by downloading them between 2010 and last year, five counts of possessing illegal pictures of children, from 2001 until January this year, and an offence of intentionally encouraging or assisting in the commission of an offence by creating internet sites and administering other websites, between 2008 and January this year.
Victoria Rose, prosecuting, said that as well as distributing child pornography, Jarvis advised other like-minded people on how to avoid detection by the police or vigilante-style internet groups.
He created "safe" areas for paedophiles to communicate online, she said.
In total the offences related to 349,643 images at level one, the least serious category of image, 764 images and 32 videos at level two, 877 images at level three, 969 images and 11 videos at level four and 60 images in the most serious category, level five.
The images were mainly of young girls.
Sentencing Jarvis, Judge Michael Pert QC said: "Anyone who even briefly viewed the material subject to these charges, as I've had to do, can see the images have come from third world countries.
"One can imagine the economic circumstances that led to these children being exploited for their creation, for the sexual gratification of others thousands of miles away.
"Your active participation in the exchange of information not only helped others to administer material to each other but also to avoid detection."
Jane Hinds, mitigating, said Jarvis had no previous convictions.
She said: "He's always had considerable technical ability.
"His interest in computers and creating web pages brought him to commit these offences.
"His interest was in images in the lower range of seriousness.
"He's been a lonely person with limited family and friends."
He lost his mother 14 years ago, and his interest in technology took a more sinister turn after that, the court was told.
Mrs Hinds said: "He's lost contact with his sibling who wants nothing more to do with him and he understands and accepts that."
Detective Constable Robert Waddington, of Leicestershire Police, said after the hearing: "This was an incredibly detailed investigation involving several agencies.
"Jarvis was responsible for distributing many thousands of indecent images of children to like-minded individuals around the world. He used his technical skills to help others to commit offences.
"Offenders such as Jarvis think they can contact, coerce and cause harm to young people via the internet, and believe they will not have to face the consequences of their actions.
"They must realise that everything done online leaves a digital footprint and we will use this information to locate them and ensure they are brought before the courts to face justice."
VIDEO: Raid on the address where Jarvis was living at the time.
