Gary Thomas Mattesich

It is with deep love and profound sadness that the family of Gary Mattesich announces his passing. Gary was a devoted husband, a loving father, a proud grandfather, and a steadfast friend whose warmth and generosity touched everyone who knew him.

Born to Tom and Dorothy Mattesich, Gary grew up in a home filled with love, encouragement, and a strong sense of family—values that shaped the man he became. Their influence remained a guiding light throughout his life. Gary is survived by his beloved wife of 63 years, RoseMarie, his devoted partner in life. He also leaves behind his cherished children, Jill Mattesich Udoutch and Tom Mattesich, who carry forward his kindness, strength, and enduring love of family. He was immensely proud of his grandchildren—Joel Udoutch and his wife Bailey, Aaron Udoutch, Sarah Udoutch, and partner Austin. Each brought him tremendous joy, and he treasured every moment spent with them. Gary is also survived by his brother, Bob Mattesich, with whom he shared a lifetime of memories, laughter, and unbreakable sibling bonds; Bob’s daughter Megan Bean and her husband Jimmy, as well as Bob’s partner, Alishia Lopez-Rivera, whose care and love added comfort and brightness to his life. A lifelong lover of the outdoors, Gary embraced adventure and found joy in nature. He cherished summer camping trips with his family to Whiskeytown Lake, and was happiest on the water, where he spent countless hours boating and waterskiing. He taught many people to ski over the years where his kindness and patience was on display, sharing not only his skill but also his enthusiasm for the lake and the freedom it offered. In winter, he found exhilaration on the slopes, especially racing down The Wall at Kirkwood—one of his favorite challenges.

A man of discipline and perseverance, Gary was also a passionate runner who completed multiple marathons, with Hawaii standing out among his most treasured experiences. He was an active member of the bike club The Valley Spokesmen, and rode his bicycle to work most days. Gary was a lifelong Raider fan and season ticket holder since the teams inception in 1960, a tradition instituted by his Father, Tom. Gary was a strong Christian and attended weekly bible study with his men’s group. Professionally, Gary was an accomplished electrical engineer, with a specialty in radiation detection. He started his schooling at UC Berkeley and finished his Masters at San Jose State, and applied his expertise with pride and commitment. He started his Career with Sandia and Lawrence Livermore Laboratory and contributed significantly during his years there. He later worked at Nuclear Data, Canberra and finished his career with the Department of Homeland Security, leaving behind a legacy of innovation and excellence that helped to

serve many people with applications in both the Medical and Security industries Gary will be remembered for his unwavering support of his family, his ready smile, and his gift for making others feel welcome and appreciated. Though he will be deeply missed, the memories he created and the love he shared will continue to live on in the hearts of all who knew him. The family invites friends and loved ones to join in celebrating Gary’s life at a later date, to be

announced.

May he rest in peace, surrounded by the light and love he so generously gave.