Peter James Nielsen (Jim), of Broomfield, Colorado, passed away on Sunday, February 22, 2026, the day after his 88th birthday, surrounded by his family. Jim was born on February 21, 1938, in North Platte, Nebraska, and was raised in Sidney, Nebraska, by his parents, Fern and Hans Peter Nielsen.
Jim excelled in both athletics and music during his youth, playing football throughout high school and studying piano before later dedicating himself to the trombone. He met his beloved wife, Joyce, while attending Midland Lutheran College in Fremont, Nebraska, where he performed in the college band and earned his Bachelor’s degree in Biology. He later pursued graduate studies at the University of Nebraska in Lincoln, NE, where he earned his Ph.D. in Physiology and Zoology in 1968 and was a lifelong Cornhusker fan.
Dr. Nielsen was a Professor of Microbiology and Physiology at Western Illinois University in Macomb, Illinois, for 35 years, where he was deeply committed to teaching, advising, and mentoring his students. Jim was active in his children’s and grandchildren’s lives, supporting their activities and accomplishments, as well as enjoying dancing and playing bridge with Joyce and their friends. He engaged in the community through his involvement with the university, Trinity Lutheran Church, and the Boy Scouts of America. He also pursued many personal interests, including riding his scooter, flying, sailing, and woodworking.
Jim and Joyce retired to Edwards, Colorado, and spent 10 years skiing together and volunteering as ski guides at Beaver Creek Ski Resort, the Vilar Performing Arts Center, and Vail’s Shaw Cancer Center. They were also active members of the Mount of the Holy Cross Lutheran Church in Vail, CO. For the past ten years they have enjoyed living on the Front Range of Colorado in Anthem Ranch and being involved in their community and the Cross of Christ Lutheran Church in Broomfield, CO.
Jim and Joyce also shared a lifelong love of travel, attending Broadway performances in New York, participating in river cruises throughout Europe, and embarking on memorable journeys, including a safari in South Africa and a trip to the Holy Land. The most memorable trip being one to Hawaii with the entire family.
Jim is survived by his devoted wife, Joyce; his three children Pam Sunderland (Mark) of Boulder, CO, Tim Nielsen (Carol) of Houston, TX , and Kristi Kraut (Jon) of Champaign, IL; his seven grandchildren, James, Nick, John, Joe, Tyler, Ryan, and Anna; and two great-grandchildren, Willa and Parker.
Jim touched many lives and will be remembered for his devotion to his family, his distinguished academic career, and his lasting influence on the many students he mentored and guided throughout his life.
A Celebration of his Life will be held at a later time in Broomfield, CO.
