The younger son of Hollywood filmmaker and political activist Rob Reiner was formally charged on Tuesday with first-degree murder in the stabbing deaths of his parents, who were found slain in their Los Angeles home over the weekend.

Nick Reiner, 32, was arrested several hours after the bodies of his father, actor-director Rob Reiner, 78, and mother, photographer-producer Michele Reiner, 70, were discovered on Sunday afternoon in the couple's house in the affluent west LA neighbourhood of Brentwood.

Officials said evidence gathered by the Los Angeles Police Department led homicide detectives to Reiner, who was taken into custody without incident on Sunday night at a park in downtown Los Angeles near the campus of the University of Southern California.

Police investigators turned over the case to the district attorney's Office on Tuesday. A five-page criminal complaint containing two counts of first-degree murder were filed against Nick Reiner later in the day in Los Angeles County Superior Court.

The killings ranked among the most shocking celebrity murders in Los Angeles history, eliciting comparisons by some to the stabbing deaths of OJ Simpson's ex-wife Nicole Brown Simpson and a friend, Ron Goldman in 1994.

"Their loss is beyond tragic," County District Attorney Nathan Hochman said of the Reiners at a news conference earlier in the day. "We will commit ourselves to bringing their murderer to justice."

Prosecutors weigh capital punishment

Hochman said the charges carry a maximum penalty of life in prison without the possibility of parole, or capital punishment, but prosecutors have yet to decide whether to seek the death penalty in the case.

He said prosecutors "will take the thoughts and desires of the family into consideration" in making such decisions.

According to the district attorney and the charging documents, a knife was used in the killings, but no further details were given about the circumstances of the slayings.

Authorities have made no mention of a possible motive.

Asked whether the murder weapon was recovered, Hochman said that would be revealed in court. Authorities said autopsies, which have to be completed, would determine the precise cause, manner and times of death.

Various news media outlets have reported that Nick Reiner had a heated quarrel with his parents on Saturday night at a holiday party hosted by comedian Conan O'Brien.

Nick Reiner, the younger of the Reiners' two sons and their middle child, has publicly acknowledged a years-long struggle with substance abuse. He has remained held without bail at a Los Angeles County lockup since he was booked on suspicion of murder on Sunday night.

Neither Hochman nor Los Angeles Police Chief Jim McDonnell would say whether Reiner was under the influence of any drugs or alcohol when he was arrested, or whether he gave any statements to police.

Prominent Los Angeles defense attorney Alan Jackson, representing Reiner, said his client had yet to be medically cleared for his initial court appearance on Tuesday, but would possibly be arraigned on Wednesday.

Obtaining medical clearance for court appearances was routine for all criminal defendants, Hochman said.

Rob Reiner's Hollywood legacy

Nick Reiner has spoken about periods of homelessness that occurred when he refused to seek treatment for substance abuse, saying he entered rehab for the first of many instances at age 15. Those experiences inspired the movie Being Charlie, co-written by Reiner and his father.

"It was the most personal thing I've ever been involved in," Rob Reiner told podcaster Marc Maron in 2016.

As an actor, Rob Reiner was best remembered for his role on the TV comedy All in the Family as Mike "Meathead" Stivic, the son-in-law and liberal foil of the lead character, working-class bigot Archie Bunker, played by Carroll O'Connor.

Reiner went on to a prolific Hollywood career as a filmmaker, directing such popular movies as This Is Spinal Tap, The Princess Bride, When Harry Met Sally..., Stand by Me, A Few Good Men, Misery and The American President.

A sequel to the mockumentary This Is Spinal Tap was released this year, 41 years after the original.

His wife, Michele, was at one time a photographer who captured the image of Donald Trump that appears on the cover of his book Trump: The Art of the Deal. She and Rob Reiner met while he was directing When Harry Met Sally and they married in 1989.

Rob Reiner, a native of New York City and son of the late comedy writer and actor Carl Reiner, also was well known for his political activism and as a supporter of the Democratic Party.

He was first married to Penny Marshall, who starred in the TV sitcom Laverne & Shirley, and was also a producer and director. He was the adoptive father to Marshall's daughter.