Frank Muellner passed away at home on February 10, 2026, in Park Ridge, Illinois at the age of 88. Born on January 29, 1938, in Chicago on the near north side, he enjoyed an active childhood, especially with his identical twin brother, the late Jack Muellner. Frank graduated from DePaul University with a degree in Physics followed by a Masters in Electrical Engineering. While at DePaul he met the love of his life, Frances Massoni, at a dance. They married in 1961 and shared 64 devoted years together. In addition to running his own business, he taught physics and calculous, and volunteered at church.

Frank was a very generous, witty, and spiritual man. Through the years he deeply loved God, his family, gardening, dancing, building things, and fixing anything and everything.

Despite facing many health challenges in his later life, he remained strong and defied the odds multiple times.

Frank was preceded in death by his parents, Frank & Catherine, his son Michael, his brother Jack, sister Ann (Tom Culhane), and sister Mary (Bob Stackley).

He is survived by his loving wife, Frances, his daughter Sharon (Tim Kordik), granddaughters Jennifer Kordik, Angela Kordik and Samatha (Joe Hamill), brothers William (Marilyn) and Robert (the late Colleen) and numerous nieces, nephews and friends.

Frank will be deeply missed and lovingly remembered.

Funeral Monday February 16, 2026, Lying in State at St. Juliana Church from 9:30 AM until the time of the Funeral Mass 10:30 AM. Interment Maryhill Cemetery.

In lieu of flowers, donations can be made in Franks honor to the Multiple Myeloma Research Foundation , St. Juliana Church , or Unity Hospice .

Funeral info: 847-966-7302