(RNS) — Few knew him by name, but many saw his signature handiwork on the sides of the road or in media images from scenes of tragedy — squat, white wooden crosses with the names of gun victims scrawled in black ink.

Greg Zanis estimated he made more than 26,000 such memorials, iconic testaments to the nation’s mass shootings.

Zanis died Monday (May 4) of bladder cancer, said his daughter, Susie Zanis, whose GoFundMe account, initially set up to support his work and his medical expenses, is now being devoted to his funeral. He was 69.

For decades, Zanis, a retired carpenter from Aurora, Ill., crisscrossed the country to erect his memorials near the sites of massacres. His crosses — many with red hearts —  were at Columbine High School, Sandy Hook Elementary School, the Boston Marathon, the Mandalay Bay hotel in Las Vegas, Marjory Stoneman Douglas High School, the El Paso Walmart and dozens of other places.

In the Chicago area alone, he put up hundreds of crosses. They included six in his hometown of Aurora after an employee opened fire in the Henry Pratt manufacturing plant last year.

“I wanted to do this when I retired, but I didn’t expect so many mass murders in this country,” he told a reporter after he arrived at First Baptist Church of Sutherland Springs, Texas, in November 2017 with 27 crosses, one for an unborn child. Two days earlier, a gunman had killed 26 people at the church and wounded 20 others.

Zanis fashioned his first cross as a tribute to his father-in-law, who was fatally shot in 1996. Eventually Zanis began to see his work as a ministry and set up a foundation, Crosses for Losses.

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Greek Orthodox by faith, he was moved to create crescents for Muslims and Stars of David for Jews. He arrived in Pittsburgh the day after the shooting at the Tree of Life synagogue where 11 Jews were killed in 2018.

Laurie Zittrain Eisenberg, who wrote an essay about the massacre for an upcoming anthology called Bound in the Bond of Life, wrote that Zanis walked the block around the synagogue for more than an hour before deciding where to set down the stars he had built.

He was concerned “he might have unintentionally offended the Jewish community by simply showing up with the stars. He seemed genuinely relieved to hear that the congregations cherished and appreciated his contribution,” Eisenberg wrote.

Zanis retired in December 2019 after receiving his cancer diagnosis and turned his project over to Lutheran Church Charities. Days before his death, a procession of cars, motorcycles and bagpipers passed by his family’s home as Zanis, sitting in a wheelchair wrapped in a blanket, watched from a stoop. The Illinois stay-at-home order prevented the well-wishers from entering his home.

His final trip was in November when he delivered crosses to Saugus High School in Santa Clarita, a city north of Los Angeles, where a student with a pistol shot five schoolmates, killing two, before killing himself.