A police officer in Southern California was likely shot to death with his own gun as he struggled with a suspected truck thief, police said Wednesday after arresting a career criminal in the weekend attack.

Riverside Police Chief Sergio Diaz said he believes Officer Ryan Bonaminio was ambushed after he pulled over the driver of a stolen big-rig cab and was led down a dark path into a park where he was shot, possibly with his own weapon.

"I do believe that this was an ambush, that this individual led our officer down a path in order to hurt him and disarm him," Diaz said during a news conference Wednesday.

The .40-caliber pistol was found during a search Wednesday morning following Tuesday night's arrest.

Police said Bonaminio was shot Sunday night after the suspect jumped from the truck and ran into a park with the 27-year old officer chasing him on foot.

They gun may have been fired at least three times, said Riverside police Det. Ron Sanfilippo, but declined to discuss other details.

The killer fled after the shooting. During the manhunt, Riverside officers staffed a phone bank around the clock that took calls from around the state, Sanfilippo said. Also, some $485,000 in rewards were offered for information.

However, it was a fingerprint found in the abandoned truck cab that finally identified the suspect, Sanfilippo said.

More than a dozen officers, including members of the Inland Regional Apprehension Team, and FBI agents descended on the Riverside Target shopping center at about 8 p.m. Tuesday and arrested Earl Ellis Green, a 44-year-old who was paroled in February 2009 and lived in nearby Rubidoux, police said.

Green was working under the hood of the truck he was driving when he was arrested, Diaz said.

After questioning by homicide detectives, Green was booked into the Robert Presley Detention Center for investigation of murder and a parole violation. Arraignment was scheduled for Monday, though the district attorney's office said he had not yet been charged.

Green was with his girlfriend, who was questioned and released, Sanfilippo said.

Green's criminal history dating back to at least 1990 and he has served jail time for vehicle theft, receiving stolen property and battery on a police officer, court records show. He was sentenced to three years in prison in 2007 for committing vandalism that caused more than $400 in damage.

Diaz said Californians often debate the cost of incarcerating inmates but not the cost of their release.

"This is what it costs to let people out with the blind hope that they'll cure themselves, that they'll rehabilitate themselves. They don't," he said.

Pete Scalisi, director of the capital defender's office in Riverside, declined to comment on the allegations.

A cousin, Eddie Green Jr., told KABC-TV that his relative "has to be disturbed" and had tried to kill an uncle on Saturday, a day before the police officer's killing.

"He just went on a rampage, tried to run him over, tried to stab him," Eddie Green Jr. said.

Police were called to the scene but said it was a civil matter, he said.

However, Sanfilippo said he was unaware of the incident.

"My condolences go out to the family members that lost a loved one and also to the community that lost an officer that was serving his community, that was doing what he was doing," Eddie Green Jr. said.

At the news conference, Bonaminio's father Joseph said he was amazed at the speed of the arrest and said his son would have been proud. He said he learned of the arrest while watching the television news Tuesday night. A video showed officers taking Green into custody.

Bonaminio said he turned off the TV and went to bed.

"I don't care what he looks like. I don't care who he is. I just want justice for my son," he said.

Bonaminio was born and raised in Riverside, a suburb of 300,000 people 60 miles east of Los Angeles. He returned to his hometown to be a police officer, as he had long intended to do, after serving Army tours in Iraq and Germany.

Funeral services will be held Tuesday for Bonaminio, who will be buried in Riverside National Cemetery.


Associated Press Writer Robert Jablon contributed to this report from Los Angeles.