DUBUQUE COUNTY, Iowa – On July 1, 2025, the Dubuque County Sheriff’s Office (DCSO) requested assistance from the Iowa Division of Criminal Investigation (DCI) with an officer-involved shooting along Highway 151 near Cascade in Dubuque County, Iowa.

At approximately 4:30 a.m. on July 1, members of the DCSO, Dubuque Police Department, Iowa Division of Narcotics Enforcement, Monticello Police Department, and Jones County Sheriff’s Office conducted a traffic stop of a vehicle on Highway 151 north of the Highway 136 interchange. The traffic stop was related to a multi-jurisdictional investigation.

During the traffic stop, the suspect in this investigation, an adult male and sole occupant of the vehicle, displayed a handgun. Shots were fired, which resulted in a DCSO sergeant, and the suspect, being struck by gunfire. The DCSO sergeant was transported to MercyOne Emergency Care in Dubuque, then to the University of Iowa Hospitals and Clinics. He was later released after being treated for a gunshot wound. The suspect, identified as James Sherrill, 36, was pronounced deceased. Sherrill was from the Linn County, Iowa area.

The officers involved have been identified as follows:

Sergeant Adam Williams, 46, an 18-year veteran of the Dubuque County Sheriff’s Office;

Officer Chad Leitzen, 49, a 23-year veteran of the Dubuque Police Department;

and Officer Cole Millard, 42, a 2-year veteran of the Monticello Police Department.

This is an ongoing investigation. No additional information will be released at this time.

Upon the conclusion of the investigation, the DCI’s investigative findings will be reviewed by the Dubuque County Attorney’s Office and the Iowa Attorney General’s Office.