(Sioux City)– A federal jury has convicted a Sioux City man on drug charges in a case with ties to Dickinson county.
The U.S. Attorney’s Office for the Northern District of Iowa says 50-year-old Jonathan Seff was convicted of conspiracy to distribute a controlled substance, distribution of methamphetamine near a protected location (an elementary school), and two counts of possession with intent to distribute a controlled substance, methamphetamine and fentanyl. The verdict was reached after about three hours of deliberation.
Seff had previously been convicted in the Northern District of Iowa for conspiracy to distribute 50 grams or more of a mixture or substance containing a detectable amount of methamphetamine, containing five grams or more of pure meth.
Evidence presented during the trial revealed from at least April 1st, 2025 to January 7th, 2026, Seff was obtaining and distributing methamphetamine from the dark web using cryptocurrency. On October 9th, 2025, Seff distributed more than 5 grams of pure meth to another person within 1,000 feet of a school in Sioux City.
On October 13th, 2025, Seff was arrested for operating under the influence after hitting a legally parked car on a Sioux City Street and flipping his own vehicle. Law enforcement confiscated over 800 counterfeit oxycodone tablets with fentanyl, more than $4,000 in cash, a digital scale with methamphetamine on it, several baggies, and Seff’s vehicle.
On January 7th of this year, the Dickinson County Sheriff’s Office was called to a home on West Lake Okoboji after getting a report of individuals trespassing at the residence, which was unoccupied. According to prosecutors, Seff had contacted an individual on a recorded jail call and sent them to the home that he had been staying at to “clean up”, directing them to specified locations in the home. Law enforcement officers located more than 10 grams of methamphetamine, a digital scale, baggies, fentanyl and what’s known as MDMA in the house.
Seff remains in the custody of a U.S. Marshal pending sentencing. He faces a mandatory minimum sentence of 10 year’s imprisonment and a possible maximum sentence of life imprisonment, an $8 million fine and 8 years to life on supervised release following any imprisonment.
