John Diaz de Leon
August 08, 1956 - April 14, 2026
Obituary
LIVESTREAM SERVICE:
John's Livestream Service will begin at 11 a.m. CT on Thursday, April 23, 2026. To view it, please scroll down to the Webcast section and click on “Watch Now.”
MADISON - John Anthony Diaz de Leon II, age 69, of Madison, passed away on Tuesday, April 14, 2026. He was born on August 8, 1956, in Milwaukee, the son of John Diaz de Leon I and Dolores “Laurie” Ulma.
John graduated from Milwaukee Hamilton High School in 1974 and received his Bachelor’s Degree in Electrical Engineering from UW-Madison in 1978. He was united in marriage to Ruth Delmore on June 6, 1987, in Madison, Wis.
John worked as an electrical engineer for Wisconsin Power & Light, Alliant Energy, and later for American Superconductor (AMSC), retiring in 2019. He was an active member of the Madison Astronomical Society, City Church of Madison (Fellowship of Christian Assemblies), the Madison Chapter BMW Club, and IEEE. He enjoyed NASCAR and Formula 1 racing, was an avid fan of the Green Bay Packers and Badgers football, collected model trains, and took great pride in restoring his 1995 Miata.
John is survived by his wife, Ruth; sons, John (Alyssa) Diaz de Leon III and Timothy Diaz de Leon; sister, Ellen (Jake) Neder; and brother, Peter (Barb) Diaz de Leon. He was preceded in death by his parents, John and Dolores “Laurie."
A funeral service will be held at GUNDERSON EAST FUNERAL AND CREMATION CARE, 5203 Monona Drive, Madison, at 11 a.m. on Thursday, April 23, 2026. Family and friends who wish to view the service via LIVESTREAM may visit John’s obituary page at www.gundersonfh.com at the time of the service and click on "Watch Now" in the Webcast section. Burial will take place at Highland Memory Gardens in Cottage Grove. Visitation will be held at the funeral home from 9 a.m. until the time of the service on Thursday.
Online condolences may be made at www.gundersonfh.com.
Gunderson East
Funeral & Cremation Care
5203 Monona Drive
(608) 221-5420