A homeless man was stabbed to death behind a busy fast-food restaurant in Anaheim late Friday, the fourth such killing in Orange County in the last month, and police quickly took a man into custody for questioning. The suspect was being chased by two bystanders when police caught him on La Palma Avenue about a quarter-mile from the scene of the crime, according to Sgt. Bob Dunn, an Anaheim police spokesman. Authorities were cautious about linking the latest killing to the previous three, but said the suspect bore a resemblance to a man being sought in those deaths, which have been called the work of a serial killer. Investigators said about 50 witnesses were being interviewed about Friday's crime, and Orange County sheriff's deputies were using bloodhounds to pore over the scene for clues. Asked if the man detained Friday looks like the man filmed in a surveillance video around the time and place of the first killing, on Dec. 20 in Placentia, Deputy Anaheim Police Chief Craig Hunter said, "Yes, in a general sense, he does." However, he said police were not assuming they had solved the serial killings. "We are certainly not letting down our guard," Hunter told reporters at an impromptu news conference near the crime scene. According to the deputy chief, police received word at 8:17 p.m. of an assault in progress, and rushed to the scene behind a Carl's Jr. restaurant on La Palma and Imperial Highway. There, they found the body of a homeless man with stab wounds near a trash bin. The victim was not identified by authorities, but Krista Schegetz, 42, of Anaheim said she knew him as John. Police cordoned off a large area around the crime scene, which was in a busy commercial area of restaurants, a movie theater and a grocery store. Detectives have enlisted the public's help, releasing grainy footage from a security camera showing a man police described as dressed in black and "lying in wait" about the time of the first attack, in Placentia.