Candles, flowers and handwritten tributes flow onto the sidewalk like surf filling a void in the sand, replacing the body just taken away. Memorials in Chinatown this week marked the spots where four homeless men were killed on Saturday, their heads smashed while they slept by an attacker wielding a metal bar.

But something else was left at the sites. Fresh boxes of hot pizza were stacked at each memorial. And with them, a note. “I wish with all my heart,” it read, “that I could have been there at that very moment to protect all of you guys.”

The author added, “you know me as the pizza guy.” Then he revealed something from his own past: “As a former homeless man, I know the struggle that all of you guys went through every day.”

The pizzas and notes came from Hakki Akdeniz, a 39-year-old immigrant who has built a small chain of pizza shops in the city and, with it, something of an unofficial, but solid, support network for the homeless in Manhattan . His visits to the memorials this week, each time lugging a stack of pizzas that reached his chin, follow a remarkable journey even in a city built on rags-to-riches tales.