SHELDON, IA (Northwestiowanow) – An illegal immigrant living in Sheldon who was previously deported has been sentenced to federal prison.

27-year-old Sergio Niz-Mendez of Guatemala was sentenced Thursday, August 6, in Sioux City to 16 months in federal prison.

Niz-Mendez pleaded guilty to illegal re-entry into the United States and failing to register as a sex offender.

Prosecutors say he was previously deported in 2018 after serving prison time for a felony conviction and had not obtained permission to legally return to the United States.

Niz-Mendez was required to register as a sex offender because of a 2016 Massachusetts conviction for rape of a child with force. Federal prosecutors say he failed to register while living in Iowa.

He was located in O’Brien County in December 2025 after being arrested on charges of operating while intoxicated and eluding.

Following his prison term, Niz-Mendez must serve five years of supervised release.