A Pierre man has been sentenced in federal court for failing to register as a sex offender, according to an announcement from United States Attorney Alison J. Ramsdell. U.S. District Judge Eric C. Schulte sentenced Archie Mack, 41, to three months in federal prison and five years of supervised release. Mack is also required to pay a $100 special assessment to the Federal Crime Victims Fund.
Mack was indicted by a federal grand jury in January 2025 and pleaded guilty on June 4, 2025.
According to court documents, Mack was convicted of Sexual Abuse of a Minor in December 2005. This conviction requires him to register as a sex offender and update his registration within three business days if he relocates or changes employment or student status. In August 2024, Mack updated his registration with an address in Pierre but failed to update it after moving to another residence in September 2024. He was arrested on November 19, 2024.
“This case was brought as a 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. Attorney’s Offices and the DOJ’s Child Exploitation and Obscenity 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.”
The investigation involved the U.S. Marshal’s Service and the Pierre Police Department. Assistant U.S. Attorney Kirk Albertson prosecuted the case.
Mack was immediately remanded into custody following sentencing.
