COUNCIL BLUFFS – Shelby County Sheriff’s Office assisted in an investigation which led to arrests of Cass County residents for conspiring to distribute fentanyl causing serious bodily injury or death, according to a report from the Southern District Court of Iowa.Collin Jacob Clarken, 21, was sentenced to 252 months in prison. Colby Ray Clarken, 25, was sentenced to 240 months in prison. There is no parole in the federal system.