Police From Around State Mourn a Fallen Comrade : Law enforcement: Large crowd attends services for Oxnard detective who was killed by gunman during rampage.

More than 3,200 law enforcement officers from across the state converged on Ventura County on Tuesday morning to pay last respects to a slain comrade, veteran Oxnard Police Detective James E. O’Brien, in a dramatic display of sympathy and solidarity.

A procession of 1,200 cars--led by hundreds of motorcycles and squad cars, some with sirens wailing--drove slowly through the cities of Camarillo and Oxnard, past onlookers who waved or simply watched the solemn, miles-long spectacle.

O’Brien was slain Thursday by a gunman who earlier had sprayed an Oxnard unemployment office with bullets, killing three and wounding four. The gunman, jobless computer engineer Alan Winterbourne, was later shot and killed by police.

“We are not here today to celebrate this man’s death; we are here to celebrate this man’s life,” said Father Liam Kidney, the pastor at O’Brien’s church, Padre Serra in Camarillo. “I know this much: If they need cops in heaven, they got a good one in Jim O’Brien.”

After the 90-minute Mass--held at St. Mary Magdalen Church in Camarillo, where it was also broadcast on speakers and television sets to a packed parking lot--the funeral procession made its way to Oxnard’s Santa Clara Cemetery. A 21-gun salute honored O’Brien after the graveside ceremony, and two helicopters flew the “Missing Man” formation overhead.

Separate funeral services were held elsewhere in Ventura County on Tuesday for the other victims of Winterbourne’s rampage. The services for Anna F. Velasco, Phillip Villegas and Richard Bateman each drew hundreds of grieving friends and family.

Velasco and Villegas worked for the state Employment Development Department, where they were known as cheerful, diligent employees. Bateman was shot while helping a developmentally disabled client test clerical skills in a real-life setting, the Oxnard unemployment office.

Even as the victims of Winterbourne’s violent outburst were being buried, detectives said they had pieced together some new facts about the 33-year-old computer engineer, who had been unemployed for almost eight years.

Winterbourne apparently had no history of mental illness or drug use, said Dr. Fred Walker, an assistant medical examiner in Ventura County. He also had owned for years the weapons he carried at his death: two high-powered rifles, a shotgun and a pistol.

Those findings led authorities to conclude that Winterbourne simply snapped after years of fruitless job searches. A memorial service for Winterbourne will be held today in Ventura.

O’Brien, a nine-year veteran of the Oxnard Police Department, devoted much of his time to combatting local gangs and wiping out graffiti.

Dozens of teen-agers attended the service, standing shyly in the parking lot to honor a cop who knew them all by name. His karate students and sparring partners came, too, remembering O’Brien as a mentor who taught them never to quit, in sport or in life.

“He was someone really special, someone who shouldn’t have died,” said Tara Mahoney, 18.

Dozens of city police departments, from Fresno to Yucca Valley, sent representatives to join the somber crowd. Los Angeles Police Chief Willie L. Williams attended, as did officers from the Federal Bureau of Investigation and U.S. Coast Guard.

“Any time a police officer is killed, you feel it, whether he’s in your department or not,” Williams said. “This is where a chief belongs.”

While the crowds at the other three funerals were not as large as the estimated 4,500 attending O’Brien’s Mass, the grief was just as intense.

At Velasco’s bilingual Mass, more than 400 friends and family listened as Father Norman Supancheck urged them to use her life as a model.

“I never saw her hurt anyone, never heard her say anything bad about anyone,” Supancheck said, recalling Velasco’s efforts to help the poor and downtrodden. “I would hope that would be our goal in life too.”

Friends of Villegas remembered him as a devoted community activist who put others ahead of himself.

“He liked people and people liked him,” said Will Berg, a friend of Villegas’ for more than 30 years. “He was magic for this community. We all die a little bit when someone like Phillip dies.”

Times staff writers Daryl Kelley, Carlos V. Lozano, Sara Catania, Jeff Meyers, Joanna M. Miller and Fred Alvarez contributed to this report in Ventura County. Times correspondents Maia Davis and Julie Fields also contributed.