Lilly K. Jansen, a 21-year-old resident of Dieterich, Illinois, passed away on Wednesday, January 28, 2026, at Barnes Jewish Hospital. Lilly, the daughter of Matthew and Leslie (Willenborg) Jansen, was born in Mattoon on August 18, 2004. She was a brilliant, driven young woman whose warmth and generosity affected everyone who met her. Her family, friends, and the Dieterich community are in deep sorrow at her untimely demise.
At Southern Illinois University Edwardsville, Lilly was diligently and enthusiastically working toward a degree in civil engineering. She was excited to start her career following her anticipated graduation in May 2026 and had already taken a position with CDI in Effingham. She demonstrated exceptional performance in difficult assignments, good peer collaboration, and a sincere enthusiasm for learning in her academic career.
At the center of Lilly’s world was her family, whom she loved deeply and unconditionally. She is survived by her parents Matthew and Leslie of Dieterich; her brother Cole of Dieterich; her sister Katelyn (fiancé Jake Herd) of Dieterich; her future fiancé Will Overton of Altamont; and her grandparents Raymond and Linda Willenborg of Teutopolis and Marilyn Jansen of Neoga.
Lilly cherished time spent with her loved ones—whether family gatherings, quiet evenings at home, or shared adventures—and always made sure those closest to her felt supported, appreciated, and loved. Her future fiancé Will was her partner in dreams and daily life, and together they looked forward to a shared future that was tragically interrupted.
A Mass of Christian Burial was held at 10:30 a.m. on Tuesday, February 3, 2026, at St. Aloysius Catholic Church in Bishop Creek, with burial in the church cemetery. Visitation was held from 4:00 p.m. to 7:00 p.m. on Monday at the church. The Dieterich and broader Southern Illinois communities continue to reflect on the profound impact Lilly made through her kindness, her bright spirit, and the joy she brought to those around her. Rest in peace, Lilly.
The family, friends and the entire community of Dieterich in Illinois are deeply devastated during this difficult time. Please, remember them in your prayers and you can also express your condolences in the comment section below.