LINCOLN, Neb. -- The Nebraska Department of Correctional Services reports that an inmate has died.

NDCS officials say that 41-year-old Atlee Mosemann died Thursday morning at the Nebraska State Penitentiary.

Mosemann was serving a 16-to-20 year sentence for second-degree sexual assault of a child out of Hitchcock County.

Officials say that the cause of his death has not been determined, but that he was being treated for a medical condition. As is always the case whenever an inmate dies in custody, an internal investigation will be conducted by a grand jury.