Police have been reviewing surveillance video from the scene of the first murder. At a news conference Wednesday, authorities released photos from the security footage that they hope will lead to the killer and a possible witness.
Police say they believe a 2000-2003 model white four-door Toyota Corolla captured in the surveillance video could belong to the suspect or a witness, who police still want to speak with.
About an hour and a half after that picture, a man wearing black is seen approaching the victim and stabbing him.
The first murder took place Dec. 21. The body of 53-year-old James McGillivray was discovered just outside of a strip mall in Placentia. He was found with multiple stab wounds.
A week later, 42-year-old Lloyd Middaugh was found stabbed to death near Santa Ana River Trail in Anaheim. Two days later, 57-year-old Paulus Smit was found stabbed to death next to the Yorba Linda Library.
Police say they believe they're dealing with a serial killer.
"We believe these murders were likely committed by the same suspect and feel he's extremely dangerous to the public," said Anaheim Police Department chief John Welter.
Police are beefing up their patrols throughout north Orange County as a result of the killings. Authorities have formed a task force involving Anaheim, Brea and Placentia police departments.
"At this time we have not ruled out the possibility that there is one or more suspects, but all of those things are still under investigation," said Anaheim Police Sgt. Bob Dunn.
Since the last killing on Friday, police have been warning homeless people to be extra cautious, specifically to avoid sleeping or camping alone in dark, secluded areas. They've been advised to stick together as much as possible and be very aware of their surroundings.
If you have information related to these murder cases, contact the Anaheim Police Department at (714) 765-1944.