SIOUX CITY, Iowa (AP) — A Nebraska man has been sentenced for his involvement in a conspiracy targeting a potential drug trafficking witness in Iowa. Federal court records say 24-year-old Andrew Nissen was sentenced Wednesday in U.S. District Court in Sioux City to 15 years and eight months. He’d pleaded guilty to conspiracy to distribute a controlled substance and use of a firearm in a drug trafficking crime.

The Sioux City Journal reports that as part of a plea agreement, charges of conspiracy to tamper with a witness by attempting to kill a person and tampering with a witness by attempting to kill a person were dismissed. Nissen, of South Sioux City, Nebraska, admits in the plea agreement that on Aug. 1 last year, he drove Isaac McDonald to a Sioux City location where McDonald shot John Mercure in order to keep him from speaking to police about drug trafficking and firearms. Mercure soon crashed into a tree but survived.

McDonald has pleaded guilty to charges for drug, weapons and other crimes.