Sioux Falls Man Sentenced to Over 2 Years in Federal Prison for Failure to Register as a Sex Offender

SIOUX FALLS - United States Attorney Ron Parsons announced today that Chief Judge Roberto A. Lange, United States District Court, has sentenced a Sioux Falls, South Dakota, man convicted of Failure to Register as a Sex Offender. The sentencing took place on October 5, 2026.

Brian Thunder Shield, age 29, was sentenced to two years and nine months in federal prison, followed by six years of supervised release, and ordered to pay a $100 special assessment to the Federal Crime Victims Fund.

Thunder Shield was indicted by a federal grand jury in January 2026. He pleaded guilty on August 3, 2026.

The conviction stemmed from Thunder Shield's failure to register as a sex offender as required by federal law between October 17, 2025, and January 15, 2026. While unregistered, Thunder Shield allegedly committed a new sex offense. Charges related to that alleged conduct were filed by the Lincoln County States Attorney's Office in March 2026 and remain pending. Thunder Shield had previously been convicted of a sex offense in federal court which requires him to register as a sex offender for the rest of his life.

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. Executive Assistant U.S. Attorney Alison J. Ramsdell prosecuted the case.

Thunder Shield was immediately remanded to the custody of the U.S. Marshals Service.