Killer of Officer Shot Himself to Death, Autopsy Reveals : Slaying: Gunman is believed to have put pistol to his head when he was spotted after eluding capture for more than 11 hours.

An unemployed hospital worker who shot and killed a 24-year-old San Diego police officer died after firing a single bullet into his head, the county medical examiner said Wednesday.

The death of Arnaldo Castillo, 34, was ruled a suicide after authorities determined that he shot himself with the same .45-caliber semiautomatic handgun he used Tuesday to kill Ronald W. Davis, a patrolman with two years on the force.

Authorities first believed that police had killed Castillo in a shootout following an 11-hour manhunt at a Southeast San Diego apartment complex.

But Homicide Lt. Dan Berglund said late Wednesday that none of the five shots fired by officers hit Castillo. The suspect’s only other wound came 11 hours earlier, just after he shot Davis. Davis’ partner, Officer Bob Anschnick, grazed Castillo with return fire, Berglund said.

“There was a bullet to his head and no other bullets,” Berglund said. “We believe the other bullet hit Castillo during the initial confrontation.”

Castillo had been hiding between two fences outside Meadowbrook Apartments--near the apartment where he had been living--before he slipped back inside the ground and between two cars. He was spotted by two teen-agers, who pointed him out to a pair of television cameramen.

The cameramen summoned police who were searching the complex. When the officers came running, Castillo fired once at police and then shot himself, police said.

Using 9-millimeter handguns, the three officers fired at Castillo five times, missing him entirely. Castillo died of a contact wound, caused by placing a gun flush against his head and firing, police said.

The day after the shooting, homicide detectives acknowledged that Davis, described as an outgoing and eager young officer with an exceptional future, may not have been warned that Castillo was armed when he and his partner were dispatched as a backup team on a domestic dispute call.

Police received a call at 4:49 a.m. Tuesday from the Meadowbrook Apartments, a low-income complex in Southeast San Diego, where someone had reported that a man had severely beaten his girlfriend.

The first officers to arrive at the scene found Lilia Bautista, 36, hiding in the bushes. Bautista said she had been assaulted by Castillo, her live-in boyfriend. She told police that Castillo had aimed a gun at her, her 9-year-old son, two female friends in the apartment and himself before saying he could not pull the trigger.

Castillo had already left the apartment and was getting ready to back out of a parking space when the patrol car with Davis and Anschnick pulled behind Castillo’s car to block his path.

Detectives said Davis briefly flashed a spotlight on Castillo, then got out of the car. Castillo also got out, spun around and fired five times, hitting Davis once in the throat and once in the shoulder, police said.

Anschnick fired about four rounds, one of which police now believe grazed Castillo in the side as he ran into the apartment complex.

After Castillo was slain, blood was found on his shoe, leading authorities to speculate that he could not have dripped onto his foot during the shootout in which he died because he was lying on his stomach, Berglund said.

On Wednesday, Berglund and Capt. Dick Toneck said they did not know exactly what information Davis and Anschnick had when they approached Castillo at 5:18 a.m. Tuesday.

“My understanding is that they knew there had been some kind of domestic violence call originally,” Toneck said. “They had some information about a suspect involved in a 242--a battery incident. Beyond that, I don’t know what the conversation was or whether they knew he was armed or not.”

Berglund and Toneck said they would be reviewing tapes of police broadcasts of the incident to determine exactly what was said.

But both men doubted that Davis could have done anything, even if he had known Castillo was armed.

“What could the officers have done differently? I’m not sure they could have done anything differently,” Toneck said. “You always want to be in a heightened feeling towards the situation you’re dealing with, but you can’t come out with your gun drawn in every situation.”

A critique of Tuesday morning’s situation will be completed to determine whether proper police procedures were followed, Berglund said.

Castillo “was intent on getting anyone who got in his way,” Berglund said. “Regardless of having a gun in your hand, he still has the advantage.”

After Castillo shot himself, police found three seven-round magazines: one in his gun, one in his pocket and one on the ground. Berglund said Castillo had reloaded his gun after he shot Davis.

Police believe Castillo had been hiding in the same area--between two rows of fences that separate the complex from an adjacent residential neighborhood--all day. At one point, Castillo had climbed to the top of the 6-foot-high fence and hid behind thick bougainvillea while police and police dogs searched nearby.

“I don’t know what he was doing up there, maybe he was working up his courage,” said Assistant Chief Cal Krosch. “It was bizarre he was there so long. He had all the opportunity in the early morning to leave. He could have gotten away so easily in the beginning with the poor visibility of the fog in the dark.”

Apartment manager Harry B. Jones said Wednesday that acquaintances of Castillo and Bautista have told him that Bautista had thrown Castillo out of the apartment several weeks ago after she started dating another man.

Bautista was beaten by a blow “of such sufficient force (Tuesday) that a doctor said it could have killed her,” Toneck said. “She had three broken vertebrae” and spent Tuesday night at a hospital, he said.

Meanwhile, funeral services for Davis are set for 2 p.m. Friday at First United Methodist Church in Mission Valley.

Davis is from Brookings, Ore., a town of about 4,000 on the Pacific just across the California border.

He and his wife, Wendy, were graduated from Brookings-Harbor High School in 1985. He was a junior vice president, senior class representative and a member of the school’s honor society, according to the Curry Coastal Pilot. He was a standout football player and track star, the newspaper said.

After serving four years in the Marine Corps, Davis joined the Police Department in October, 1989. He won the Jerry Hartless Award for inspiration upon graduation from the Police Academy. Hartless was the last officer to die in the line of duty, when he was killed in 1988.

“It’s hit all of us hard,” Berglund said. “When anybody gets killed in the line of duty, I think it affects all of us. Makes us feel like we’re vulnerable.”