OMAHA, Neb. (AP) — A former acting director of cyber security at the U.S. Department of Health and Human Services has been sentenced to 25 years in prison for engaging in a child pornography enterprise.

The U.S. Attorney’s Office for Nebraska says 56-year-old Timothy DeFoggi, of Maryland, was sentenced Monday on charges of engaging in a child exploitation enterprise and related charges. He was convicted in August.

Prosecutors say DeFoggi used an anonymous computer network in 2012 to access child pornography and exchange private messages about illegal activity involving children. The network’s users used advanced technology to try to avoid identification.

DeFoggi is the sixth person to be convicted as part of an investigation into three child pornography websites — including one based and administered from Nebraska.