A United States Air Force airman pleaded not guilty to receiving child sex abuse materials while working on base in New Jersey.

Officials say Christian Keilberg, of Ocean County, is facing up to 20 years in prison.

Federal prosecutors say that between 2020 and 2022, Keilberg was on active duty at Joint Base McGuire-Dix-Lakehurst and communicated with underage victims. Prosecutors say he convinced the victims to send explicit photos.

Officials say a search of Keilberg's devices revealed more than 600 images of child sex abuse materials with children between the ages of 12 and 15.