SIOUX FALLS, S.D. — Three men have recently been sentenced in federal court for their roles in transporting large quantities of methamphetamine and fentanyl from California into the Sioux Falls region.
Michael Thomas, 51, of Delano, California, received a 21-year federal prison sentence for conspiracy to distribute methamphetamine and fentanyl. According to the U.S. Attorney’s Office, investigators with the FBI and Minnehaha County Sheriff’s Office uncovered a large group of people selling methamphetamine and fentanyl around Sioux Falls in 2021 and 2022. Thomas helped direct the drug-trafficking operation while he was incarcerated in a California prison.
Investigators say Thomas worked with another inmate to coordinate massive drug shipments—sometimes as large as 100 pounds of methamphetamine at a time—using semi-trucks to move the drugs from California to Sioux Falls and other locations. The drug network stretched into California, South Dakota, Oklahoma, Arkansas, Alabama and West Virginia.
In total, investigators believe Thomas helped organize the shipment of 300 to 400 pounds of methamphetamine and more than 100,000 fentanyl-containing pills. So far, 15 people connected to the operation have been convicted and sentenced in South Dakota.
One of those defendants, Darrel Devorce, 56, was sentenced to 33 years in federal prison for conspiring to distribute methamphetamine and conspiracy to commit money laundering. Investigators with Homeland Security Investigations, IRS Criminal Investigation and the Sioux Falls Area Drug Task Force say Devorce ran a large methamphetamine operation for roughly five years. Beginning in 2018, he sourced methamphetamine from California and arranged deliveries to co-conspirators in Sioux Falls. He also directed others to send and receive drug-proceeds using CashApp, Western Union and Zelle to hide the source of the money.
In another recent case, William Soudap Somphanthabansouk, 29, of Mountain Lake, Minnesota, was sentenced to 10 years in federal prison for conspiracy to distribute a controlled substance.
Investigators say Somphanthabansouk obtained methamphetamine through the mail from California and distributed it in Sioux Falls and western Minnesota. In early 2025, law enforcement learned he had traveled to California and shipped a package to himself. They stopped him on his way back to Sioux Falls, finding about 228 grams of methamphetamine and a loaded handgun in his vehicle.
A subsequent search of his home uncovered roughly 850 grams of methamphetamine and multiple guns. Investigators estimate he distributed around nine pounds of methamphetamine in the area.
Somphanthabansouk’s case was investigated by the Drug Enforcement Administration, the U.S. Postal Inspection Service and the Worthington Police Department.
