The mother of a Los Angeles County sheriff's deputy who was ambushed and killed on duty is devastated that district attorney George Gascón isn't pursuing the death penalty.

"It just seems that the district attorney wants to spare a life, when [the suspect] didn't spare my son's life -- he executed my son," Kim Clinkunbroomer, the mother of slain Los Angeles County sheriff's deputy Ryan Clinkunbroomer, told ABC News in an exclusive interview.

Deputy Clinkunbroomer, 30, was in uniform and in his patrol car when he was shot while stopped at a red light outside the Palmdale Sheriff's Station.

LA County District Attorney George Gascón repeated his opposition to the death penalty during a news conference last week alongside sheriff's officials and the Clinkunbroomer family.

"The death penalty doesn't serve as a deterrent," Gascón said, according to ABC Los Angeles station KABC.

The suspected killer, 29-year-old Kevin Salazar, is charged with murder with special circumstances. If convicted he'll face life in prison without the possibility of parole, prosecutors said.

Salazar's attorney has entered a plea of not guilty and a dual plea of not guilty by reason of insanity on his behalf.