With heavy hearts, we announce the passing of Karl Tetsuya Koessel, beloved father, grandfather, son, and brother, who died on February 23, at the age of 72.

Karl was a brilliant technical editor, a lifelong civil liberties advocate, and a founding member of PC World magazine. Known for his sharp wit, deep intellect, and singular focus, Karl inspired those around him with his boundless curiosity, kindness, and commitment to truth.

He is survived by his daughter Melisa Koessel-Verderame; his sons Noah and Sam Koessel; his step-sons David Sanchez and Elliot Felde; his grandchildren Elin Campbell, Benjamin Walters, and Isaac Walters; and his great-grandson Theodore Walters. He is also survived by his mother, Kiyoko Yamada, and his six siblings: Kurt, Eric, Konrad, Sophia, Earl, and Edwin.

A memorial celebration of Karl’s extraordinary life will be held on Saturday, July 12, 2025, at 1:00 PM, at 129 Carmel Ave, Modesto, CA. All who knew and loved him are warmly invited to attend. Please bring your memories and stories to share. 

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