LOS ANGELES (AP) — Los Angeles County prosecutors expect to file charges Wednesday against a man who allegedly shot and killed a sheriff’s deputy as he sat in a patrol car, authorities said.

Officials say Kevin Cataneo Salazar ambushed 30-year-old Deputy Ryan Clinkunbroomer on Saturday in Palmdale, a city of more than 167,000 residents in the high desert of northern Los Angeles County.

Cataneo Salazar, 29, is scheduled to be arraigned Wednesday, spokesperson Venusse Navid of the Los Angeles County district attorney’s office said in an email. The district attorney’s office has not said what charges they are pursuing in the case, but planned an afternoon news conference.

Cataneo Salazar was arrested Monday after an hours-long standoff with sheriff’s deputies. He had barricaded himself inside his family’s Palmdale home.

Questions remained in the days after the slaying, including the motive in the case and whether Clinkunbroomer and Cataneo Salazar previously knew each other.

The Los Angeles County public defender’s office did not immediately know whether they would be appointed to represent Cataneo Salazar. His mother and other family members did not return phone and email messages seeking comment.

His mother, Marle Salazar, told the Los Angeles Times her son was diagnosed as paranoid schizophrenic about five years ago. He would say he was hearing voices in his head, she said, and sometimes claimed that cars or people were following him. He twice attempted suicide, she said.

“My son is mentally ill, and if he did something, he wasn’t in his full mental capacity,” she said in an interview with the paper.

Marle Salazar told the Times that she didn’t know her son owned a gun, but she was told by detectives that he had legally purchased a weapon that was used in the attack. It was not clear when he bought the firearm.

Under California’s so-called “red flag law” — the first of such legislation to be enacted in the country — firearms can be seized from people who are considered a danger to themselves or others. Law enforcement and family and household members, as well as some co-workers, employers and teachers, can petition the court to remove the guns from the person’s possession or bar the person from purchasing them.

Despite Cataneo Salazar’s reported schizophrenia diagnosis, it was not clear whether he would have qualified under the state’s red flag law or other statutes designed to keep guns out of the hands of people with mental illnesses.

There were no Los Angeles County court records indicating someone had petitioned to seize his weapons or prevent him from buying them.

Marle Salazar said that her son had been hospitalized in the past year, but it was not clear if he sought treatment himself or was involuntarily committed.

She said she called deputies at least twice in the past, asking for help when her son refused to take his medication and grew aggressive toward himself. She said he had never hurt anyone before, and his aggression was always self-directed.

“I have called the police several times,” she told the newspaper. “In the end, they would say, ‘He’s an adult, so if he doesn’t want to take (his medication), we can’t do anything.’ ”

Sheriff’s department spokesperson Nicole Nishida previously said investigators were looking into whether there were law enforcement calls at the home.