Alison J. Ramsdell U.S. Attorney | U.S. Attorney for the District of South Dakota
A Rapid City man has been sentenced to 25 years in federal prison for his involvement in a methamphetamine distribution conspiracy. Guillermo Calderon, also known as "Memo," was sentenced by U.S. District Court Judge Karen E. Schreier on June 6, 2025. In addition to the prison term, Calderon will serve five years of supervised release and pay a $100 special assessment to the Federal Crime Victims Fund.
U.S. Attorney Alison J. Ramsdell stated, "Methamphetamine is ravaging communities throughout South Dakota, leaving a trail of heartbreaking addiction in its path." She emphasized Calderon's significant role in trafficking methamphetamine into Rapid City and the Pine Ridge Reservation.
Special Agent in Charge Alvin M. Winston Sr. of FBI Minneapolis remarked on Calderon's operation: "Calderon led a dangerous operation that funneled large amounts of methamphetamine into Pine Ridge and Rapid City, bringing violence and addiction into vulnerable communities." He added that the sentencing reaffirms efforts to bring those involved with cartel-linked drugs to justice.
Calderon was indicted by a federal grand jury in February 2024 and pleaded guilty on March 26, 2025. The investigation revealed that he led a conspiracy distributing large quantities of methamphetamine sourced from Mexican cartel operatives into the community. During his operations, Calderon used firearms and threats of violence.
In January 2024, Iowa law enforcement arrested Calderon while transporting approximately 20 pounds of methamphetamine to South Dakota. Judge Schreier noted that Calderon's actions severely impacted the South Dakota community and identified him as the most culpable member of the drug conspiracy.
The case was investigated by multiple agencies including the Oglala Sioux Tribe Department of Public Safety, Bureau of Indian Affairs, Drug Enforcement Administration, and FBI. Assistant U.S. Attorney Anna Lindrooth prosecuted the case.
Following his sentencing, Calderon was remanded to the custody of the U.S. Marshals Service.
