After a third man, identified as Paulus Smit, 57, was found dead outside a library in Yorba Linda on Dec. 30, police formed a task force with five agencies, including the FBI, to investigate the killings. Two days earlier, police had found Lloyd Middaugh, 42, near a riverbed trail in Anaheim. Investigators believe the deaths are the work of a serial killer.

Fliers with a grainy photograph of the suspected killer taken on a surveillance camera and a white Toyota Corolla believed to be connected to the crimes were handed out to drivers.

One by one, drivers were stopped and questioned by law enforcement officials involved with investigating three killings of homeless men that are believed to be connected, the first of which occurred Dec. 20.

A street outside the Placentia shopping center where a homeless man was killed became an arena for questioning Tuesday night, as police continued to search for a suspected serial killer .

In an effort to generate more tips and contacts in the community, police interviewed hundreds of drivers and vehicle passengers -- many of whom were on their way home -- about any knowledge of the crimes, and in particular, if they knew James Patrick McGillivray, 53, the first victim to be stabbed to death.

Some people nervously shook their heads when asked whether they knew anything about the crime. Others, such as Naomi Frenzel, 21, complimented police.

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Frenzel, who said she lived down the street, was still in her white EMT uniform when she was stopped by FBI agents.

"If anything does pop up, I'll give you a call," she told two men, one clutching a clipboard. She added she has the non-emergency police number programmed into her cellphone.

Others were on their way to grab dinner or a quick coffee at a nearby Starbucks.

A woman driving a black Yukon told officials she drives the route nearly every day. She had seen McGillivray on the streets occasionally but had never spoken with him. She didn't know anything about the white car, either.

"I'm out here all the time," she said. "I see so many white cars."

She wished the agents luck in catching the killer.

"I hope you guys catch this guy," she told police before driving away.

Sgt. Bob Dunn, the spokesman for the Anaheim Police Department, said this is the first time in recent memory that he can recall a roadblock such as this occurring in Orange County. But, he said, it shows a commitment to catching the killer and could prove useful for investigators.

"We want as many people to drive by as possible," he said.

At the end of the night, he was hopeful.

"We definitely have information we can follow up on," he said, as investigators began gathering orange cones.

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-- Nicole Santa Cruz

Photo: A motorist holds a flier distributed by law enforcement officials Tuesday at a roadblock in the 200 block of North Bradford Avenue in Placentia that requests information on the homicides of three homeless people in north Orange County. Credit: Anne Cusack / Los Angeles Times