Suspect Arrested for Alleged 'Execution' of Sheriff's Deputy in California

— -- A 36-year-old man has been arrested in connection with the killing of a police officer who was shot twice in the head while responding to a call this weekend near Modesto in northern California, authorities said.

David Machado was arrested about 150 miles south in Tulare County around 12:30 p.m. Sunday after he allegedly tried to steal a woman’s purse at a convenience store, according to a statement from the Stanislaus County Sheriff's Department. Machado is also suspected of a carjacking and a previous theft of a van, the statement said.

He has since been taken to Stanislaus County where he is in custody and awaiting charges, the Stanislaus County Sheriff told ABC News.

Stanislaus County Sheriff’s Deputy Dennis Wallace was shot while answering a call at about 8:25 a.m. Sunday about a suspicious van near Fox Grove Fishing Access in Hughson, about 10 miles from Modesto, according to the Sheriff's Department release.

Wallace was alone at the time but called for backup after a dispatcher told him the van was stolen and that the suspected thief, whom the dispatcher identified as Machado, was "possibly armed," the statement said.

Moments after Wallace called for assistance, "attempts to reach the deputy over the radio were unsuccessful," the statement said. When backup officers arrived on the scene, they found Wallace near his patrol car suffering from what were apparently two shots to the head at point-blank range. He was taken to a hospital, where he later died.

The van and suspect were not at the scene when the assisting officers found Wallace, and police broadcast a message to all area law enforcement agencies to help them in the search.

"We believe that Deputy Wallace was killed outside of the car, and we know for a fact that the gun used in this crime was in direct contact with his head when the trigger was pulled twice," Stanislaus County Sheriff Adam Christianson said at a news conference Sunday. "This was an execution."

About 15 minutes after Wallace had responded to the call about the suspicious van, police responded to a reported carjacking in the community of Keyes in the same county. "The victim in the carjacking identified David Machado as the suspect," the Sheriff's Department statement said.

Police then broadcast information about Machado throughout the state as the manhunt continued.At 12:33 p.m., the Stanislaus County Sheriff's office heard from police in Lindsay in Tulare County, about 150 miles south of where the carjacking occurred. Lindsay police had arrested Machado after he allegedly tried to steal a purse from a woman in a convenience store.

Once Machado was in custody, Lindsey police identified him as the suspect wanted in Stanislaus County, Sheriff Christianson said at the news conference.

"We expect the district attorney to file a criminal complaint today," with the arraignment tomorrow, Christianson told ABC News today.

A vigil for Wallace held in Hughson on Sunday night drew hundreds of people, according to ABC affiliate KXTV in Sacramento. Among those who spoke was the fallen officer's brother, Dave Wallace, who said he is also in law enforcement as was his and Dennis’ father.

"We truly loved each other,” Dave Wallace said of his brother. “And I can tell you that Dennis fully loved this community … We were both sons of a law enforcement officer. That's all he ever wanted to do as kids. We were both able to fulfill that dream."

The Associated Press contributed to this story.