After completing an internship and pathology residency at the University of Washington, Dr. Knierim began to work as a pathologist and laboratory physician at Sacred Heart Medical Center in Spokane, Washington.
Shortly after, he joined the U.S. Army and served as a pathologist at the United States Army Hospital in Okinawa, Japan, as well as Madigan Army Medical Center in Fort Lewis, Washington. Upon completing his military service, he returned to Sacred Heart Medical Center to continue his work there.
Throughout his career, Dr. Knierim has held various professional appointments, including medical director, co-chair, director, and consultant. He also worked as a clinical associate professor at the University of Washington School of Medicine Department of Pathology for over 20 years and has been a member of numerous professional organizations. He and his wife, Claire, currently live in Bellevue, Washington, and have two children, Amy and Alex.