SIOUX FALLS, S.D. (KELO) -- A convicted sex offender is headed back to prison.

Monday, a federal judge sentenced 46-year-old Matthew Zook to ten years behind bars for attempted enticement of a minor.

Zook is already on the state's sex offender registry for raping a 14-year-old girl in 2012.

This latest crime also involved a 14-year-old victim who he met on Snapchat. Authorities arrested him when he showed up at the girl's house to have sex.

Zook is a former staff sergeant at Ellsworth Air Force Base.

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