NEW YORK (CBSNewYork) — Police are trying to track down a man in new surveillance video allegedly connected to the deadly stabbing of a good Samaritan who tried to stop a robbery in Brooklyn . Yong Zheng , 46, was killed on Feb. 26 after he intervened in what turned out to be a robbery of an illegal gambling den in Sunset Park . Zheng, who was returning from dinner with his family, saw the victims of the robbery confront the suspects and believed it may have been another anti-Asian hate crime . Zheng ran over to help and was stabbed four times by the suspected robbers. The three robbery victims were also stabbed, but are expected to be OK. Zheng was the sole provider for his family, working as a bus driver. The community has set up a fundraiser for his two young children. To donate, visit gofund.me/85622e18 . Police arrested 45-year-old William Smith for Zheng’s murder, but sources said at least two other accomplices were on the loose. Anyone with information is asked to call the NYPD’s Crime Stoppers hotline at 1-800-577-TIPS (8477), or for Spanish, 1-888-57-PISTA (74782). You can also submit a tip via their website or on Twitter, @NYPDTips . All calls are kept confidential.