Joliet, Ill. (WBBM) – A former custodian at a southwest suburban high school was sentenced to 15 years in federal prison for possession and transporting child porn.

Anthony Skoien, 48, of Joliet worked at Plainfield South High School at the time of his arrest in August 2010. In February, he pleaded guilty to making thousands of pornographic images of children which he made available on a file-sharing network.

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According to a press release from the U.S. Attorney’s office, nearly 6,000 of the 7,500 children have been identified. Another 1,500 have not. The images showed the kids engaged in sexual, sadistic, and masochistic conduct. Some of them were pre-pubescent.