Zimmerman went on to be Arizona Rep. Gabrielle Giffords' community out reach director, organizing the "Congress on Your Corner" event where the shooting took place in Tucson.
Zimmerman's father said, "We remember Santa Cruz very fondly. He did well and really loved the school and made some close friends there. I was very pleased with the education he got."
In a statement, UCSC Chancellor George Blumenthal called Zimmerman's death "a tragic loss for all of us."
"On behalf of the entire UC Santa Cruz community, my wife Kelly and I extend our heartfelt condolences to Gabriel Zimmerman's family, friends and colleagues," Blumenthal said. "Gabe's work on behalf of the people of Arizona's 8th congressional district reflected his passionate commitment to the value of public service."