California police on Sunday captured a "known criminal" accused of shooting a sheriff's deputy twice in the head at point-blank range after the officer discovered the suspect in a stolen vehicle.

Multiple tactical units had been engaged in the manhunt for David Machado, 36, who is alleged to have carjacked a driver in Keyes just minutes after he murdered Stanislaus County Sheriff's Deputy Dennis Wallace on Sunday morning.

"We know the gun used in the crime was in direct contact with [Wallace's] head when the trigger was pulled twice," Sheriff Adam Christianson said during a news conference. "This was a direct execution."

Machado was already wanted on a felony warrant for unspecified criminal activity when Wallace, in his uniform and driving a marked police vehicle, entered the Fox Grove Recreation and Fishing Access park at 8:24 a.m. Wallace spotted a suspicious vehicle and, after a dispatcher told Wallace the vehicle was stolen, he requested backup.

Moments later, Wallace was dead.

By the time backup arrived, the suspect was gone. The subsequent carjacking of a Kia Rio occurred at 8:40 a.m. local time. The carjacking victim identified Machado as the man who stole the car, police said.

Machado later abandoned the stolen van and carjacked an escape vehicle in the nearby city of Keyes, according to the sheriff's department. He was arrested hours later 150 miles south of Hughson in the town of Lindsay after he tried to steal a woman's purse at a convenience store, Christianson said.

The woman fought Machado and called Lindsay police, prompting him to run from the scene. Officers chased after him on foot and took him into custody without incident, Christianson said.

Lindsay officers didn't initially recognize Machado as the suspect in the killing of Wallace. But once he was in custody, they identified him through tattoos and a photograph and immediately contacted the Stanislaus County Sheriff's Department, Christianson said.

Wallace, 53, was a 20-year veteran of the department who Christianson said was well known for his involvement in community programs such as D.A.R.E.

"Unfortunately, we do this far too often here in California and nationwide," Christianson said. "You have to ask yourself the question: 'Where does it stop, where does it end?'"

Wallace is the fourth officer killed in the line of duty in SCSD history, according to the department's website. The previous death occurred in April 2012 when Deputy Sheriff Robert Paris was gunned down while serving an eviction notice.

Stanislaus County is located in the Central Valley of California. The county seat is Modesto.

The Associated Press contributed to this report.