Source: Office of United States Attorneys
RAPID CITY – United States Attorney Alison J. Ramsdell announced today that U.S. District Court Judge Karen E. Schreier has sentenced a Rapid City, South Dakota, man convicted of Conspiracy to Distribute a Controlled Substance.
Guillermo Calderon, a/k/a “Memo,” age 38, was sentenced on June 6, 2025, to 25 years in federal prison, five years of supervised release, and a special assessment to the Federal Crime Victims Fund in the amount of $100.
“Methamphetamine is ravaging communities throughout South Dakota, leaving a trail of heartbreaking addiction in its path,” said U.S. Attorney Alison J. Ramsdell. “Calderon played a significant role in perpetuating this problem by trafficking methamphetamine into Rapid City and within the Pine Ridge Reservation. Thanks to our skilled federal and tribal law enforcement partners, Calderon will now spend serious time in federal prison.”
“Calderon led a dangerous operation that funneled large amounts of methamphetamine into Pine Ridge and Rapid City, bringing violence and addiction into vulnerable communities,” said Special Agent in Charge Alvin M. Winston Sr. of FBI Minneapolis. “Today’s sentencing reaffirms that those who bring cartel-linked drugs into our communities will be brought to justice. The FBI will continue to work with our federal, state, local, and tribal partners to disrupt drug trafficking networks and protect our communities from the devastating impact of cartel-sourced narcotics.”
Calderon was indicted by a federal grand jury in February 2024, and pleaded guilty on March 26, 2025. The investigation showed that Calderon and others distributed significant amounts of methamphetamine in Pine Ridge and Rapid City. Calderon was the leader of the conspiracy, trafficking significant amounts of methamphetamine into the community from Mexican cartel operatives. Calderon utilized firearms and threats of violence throughout his drug distribution scheme. In January 2024, Iowa law enforcement arrested Calderon while he was driving approximately 20 pounds of methamphetamine to South Dakota.
In sentencing Calderon, Judge Schreier denounced how Calderon’s actions severely damaged the South Dakota community, and found he was the most culpable and violent member of the drug conspiracy. Judge Schreier also noted the drugs Calderon distributed constituted 100% pure methamphetamine and came from a Mexican cartel.
This case was investigated by the Oglala Sioux Tribe Department of Public Safety, Bureau of Indian Affairs, the Drug Enforcement Administration, and the FBI. Assistant U.S. Attorney Anna Lindrooth prosecuted the case.
Calderon was immediately remanded to the custody of the U.S. Marshals Service following sentencing.