RAPID CITY, South Dakota — A Spearfish man has been sentenced to five years and 11 months in federal prison for possessing unregistered firearms, after investigators found unregistered silencers in a vehicle and nine homemade explosive devices at his home, the U.S. Attorney's Office for the District of South Dakota announced.

Source: U.S. Department of Justice, District of South Dakota

Cole Nygaard, 45, was sentenced on October 19, 2026, by U.S. District Judge Camela C. Theeler, after pleading guilty on July 20 to two counts of possession of an unregistered firearm. He will also serve three years of supervised release after prison and was ordered to pay $200 in special assessments. There is no parole in the federal system.

According to prosecutors, the case began in January 2024 in Lawrence County, when officers stopped a vehicle while looking for its driver after reports that he intended to kill someone. Nygaard was a passenger. Inside the car, officers found three firearms fitted with silencers that had no markings or serial numbers and were not registered in the National Firearms Registration and Transfer Record, as federal law requires.

Source: KOTA Radio, Rapid City

In a separate investigation, officers searched Nygaard's residence on January 27, 2026, after learning he was allegedly making pipe bombs and had indicated he would use them on other people and a business, prosecutors said. Inside, they found nine improvised explosive devices he had manufactured, including metal pipe bombs and a victim-operated metal box that could be assembled into a destructive device. One of the smaller devices detonated while officers were attempting to render it safe; prosecutors said precautionary measures meant no one was injured.

U.S. Attorney Ron Parsons announced the sentence. Federal law requires silencers and destructive devices to be registered; possessing unregistered ones is a federal crime, which is what Nygaard admitted in his guilty plea.