Illegal Alien Sentenced to Federal Prison for Illegal Re-entry and Failure to Register as a Sex Offender

A man who pled guilty to illegal reentry and failure to register as a sex offender was sentenced August 6, 2026, to more than a year in federal prison.

Sergio Niz-Mendez, age 27, from Guatemala and living in Sheldon, Iowa, received the prison term after a March 23, 2026, guilty plea to one count of illegal re-entry and one count of failure to register as a sex offender.

At the guilty plea, Niz-Mendez admitted he was a citizen of Guatemala, that he had previously been removed from the United States in 2018 after serving prison time for a felony conviction in 2016, and that he had not sought permission to legally be in the United States. He further admitted that due to his 2016 rape of a child with force conviction in Massachusetts, committed when he was 15 years old, he was required to register as a sex offender, which he failed to do while living in Iowa. In December 2025, Niz-Mendez was found in O'Brien County, Iowa, after he was arrested for operating while intoxicated and eluding.

Niz-Mendez was sentenced in Sioux City by United States District Court Judge Leonard T. Strand. Niz-Mendez was sentenced to 16 months' imprisonment. He must also serve a five-year term of supervised release after the prison term. There is no parole in the federal system. Niz-Mendez is being held in the United States Marshal's custody until he can be transported to a federal prison.

This case was part of Operation Take Back America a nationwide initiative that marshals the full resources of the Department of Justice to repel the invasion of illegal immigration, achieve the total elimination of cartels and transnational criminal organizations (TCOs), and protect our communities from the perpetrators of violent crime.

The case was prosecuted by Assistant United States Attorneys Patrick T. Greenwood and Shawn S. Wehde and was investigated by the Department of Homeland Security.

Court file information at https://ecf.iand.uscourts.gov/cgi-bin/login.plLinks to other government and non-government sites will typically appear with the "external link" icon to indicate that you are leaving the Department of Justice website when you click the link..

The case file number is 25-CR-4065.

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