An HIV positive paedophile who groomed teenage boys on the internet and filmed himself having sex with his victims has been jailed for life and told he must serve at least 10 years before he is considered for release.
Anthony Marsh, 53, was jailed at Sheffield Crown Court along with another paedophile, Lee Davis, 39, who was also given a life term and told he must serve at least 12-and-a-half years in prison.
Judge Julian Goose QC told Marsh and Davis they were "predatory, dangerous paedophiles".
Police have described their activities as "vile, horrendous offences".
The pair, who are both married with children, used social networks such as Facebook and Bebo, as well as specialist gay websites, to befriend boys.
After grooming teenagers as young as 13 online, salesman Marsh and unemployed Davis met their victims and sexually abused them.
Police found a library of films hidden in the cellar of Davis's home showing him abusing the boys.
Officers also established that Marsh distributed some footage shot by Marsh over the web.
Speaking outside court, Detective Inspector Delphine Waring, of South Yorkshire Police, said: "Today's sentencing brings to a conclusion one of the most shocking series of sexual crimes committed against young boys that South Yorkshire Police has investigated.
"Marsh and Davis indulged their own depraved and criminal desires for many years against a number of young, impressionable and vulnerable young boys the length and breadth of the country.
"The extent of their offending was matched only by the duplicity of their behaviour, which included their use of pseudonyms and multiple mobile phones to disguise their true identities and the deceit they exhibited day after day to their own families."
Ms Waring said Marsh's crimes were "especially deplorable".
"Knowing he had HIV, he chose to engage in sexual conduct with teenage boys and, in so doing, demonstrated a complete disregard for their wellbeing and future health.
"But, for Marsh and Davis's victims and their own families, today's sentencing will not be the end of the story.
"The damage these two men have inflicted will last for many years to come."
The detective said it was possible more victims had not yet identified themselves and urged any people in that position to come forward for help.