OMAHA, Neb. (AP) — A 27-year-old Sudanese man has been given 21 months in federal prison for not registering as a sex offender in Nebraska.

A news release from the office of U.S. Attorney Deborah Gilg says Koang Tang must serve five years of supervised release after he leaves prison.

Tang was convicted in Nebraska’s Hall County of attempted sexual assault and sentenced in February 2010 to five years of probation. Gilg’s office says Tang was taken to Des Moines, Iowa, for deportation proceedings. When Sudanese officials refused to accept him, in August 2010 he returned to Nebraska,

Gilg’s office says Tang didn’t register as required when he began living in Omaha.