Mark S. Koehler, 71, died unexpectedly on October 3, 2025, at his home in Downers Grove, Illinois. Mark was born January 10, 1954, in Merrill, Wisconsin. He was the son of the late Myron and Jane (Zimmerman) Koehler.
Mark earned associate degrees at Northcentral Technical College and UW Marathon Center in Wausau, Wisconsin. He was recruited after graduation by AT&T (Bell Labs) in 1976. He worked for many years as a computer programmer for AT&T in Naperville, Illinois. Mark traveled to various parts of the country through his job as he wrote software that was utilized in upgrades. Later, he worked for Lucent Technologies. He was often called upon by his superiors to train newcomers to the team.
Mark was a man of many interests and talents including music, astronomy, dancing, and cooking. In high school, he got interested in astronomy and built a telescope. He attended the astronomy club and volunteered in the planetarium at Wausau West High School. As a young man, he and a dance partner wowed their friends with their skillful moves on the disco dance floor. Later, he shared his love of classical piano by playing spontaneous concerts for his friends and neighbors at his apartment. He liked science fiction movies and was a devoted, “trekkie.” Once, he actually met his heroes Leonard Nimoy, James Doohan, and George Takei in person. He loved to cook and bake and kept family updated on new recipes.
Mark felt proud to have grown up on a family farm in the town of Berlin, Marathon County. He made many trips back home over the years to help family with hay baling and other farm jobs. He enjoyed sitting around the kitchen table sharing stories, eating home grown food, and laughing. We will miss him so much.
Mark is survived by his brother, Gerald Koehler and sister-in-law, Sue Kruger, of Merrill, Wisconsin. He enjoyed the company of many cousins over the years. Arrangements by Adams-Winterfield and Sullivan Funeral Home. A celebration of life will be held at Adams-Winterfield and Sullivan Funeral Home in Downers Grove at a later date.
