South Dakota Man Sentenced to 18 Months in Federal Prison for Failure to Register as a Sex Offender

SIOUX FALLS - United States Attorney Alison J. Ramsdell announced today that U.S. District Judge Karen E. Schrier has sentenced a South Dakota man convicted of Failure to Register as a Sex Offender. The sentencing took place on February 24, 2025.

Sonny Gray Grass, 63, was sentenced to one year and six months in federal prison, followed by five years of supervised release, and ordered to pay a $100 special assessment to the Federal Crime Victims Fund.

Gray Grass was indicted for Failure to Register as a Sex Offender by a federal grand jury in November 2024. He pleaded guilty in December 2024.

Gray Grass was previously convicted on September 9, 2013, in U.S. District Court for the District of South Dakota, of Abusive Sexual Contact, in violation of 18 U.S.C. §§ 1153, 2244(a)95) and 2246(3), and was, thereafter, required to register under the Sex Offender Registration and Notification Act. The conviction stems from Gray Grass failing to register his location while living in Sioux Falls in August 2024.

This case was brought as part of Project Safe Childhood, a nationwide initiative to combat the growing epidemic of child sexual exploitation and abuse, launched in May 2006 by the Department of Justice. Led by the U.S. Attorneys’ Offices and the DOJ’s Child Exploitation and Obscenity Section, Project Safe Childhood marshals federal, state, and local resources to locate, apprehend, and prosecute individuals who exploit children, as well as identify and rescue victims. For more information about Project Safe Childhood, please visit https://www.justice.gov/psc.

This case was investigated by the U.S. Marshals Service. Assistant U.S. Attorney Connie Larson prosecuted the case.

Gray Grass was immediately remanded to the custody of the U.S. Marshals Service.