Rob Reiner's son was charged on Tuesday with two counts of first-degree murder in the killing of his parents, which stunned their communities in Hollywood and Democratic politics, where both were widely beloved.

Nick Reiner, 32, is charged with killing the 78-year-old actor and director Rob Reiner and his wife, Michele Singer Reiner, District Attorney Nathan Hochman announced at a news conference with LA Police Chief Jim McDonnell.

"Their loss is beyond tragic and we will commit ourselves to bringing their murderer to justice," Hochman said.

Along with the two counts of first degree murder, prosecutors added special circumstances of multiple murders and a special allegation the defendant used a dangerous weapon, a knife.

The additions could mean a greater sentence.

Hochman said his office has not yet decided whether to seek the death penalty in the case.

"This case is heartbreaking and deeply personal, not only for the Reiner family and their loved ones but for our entire city," McDonnell said.

"We will continue to support the Reiner family and ensure that every step forward is taken with care, dignity and resolve."

The announcement came two days after the couple was found dead from apparent stab wounds in their home in the upscale Brentwood neighbourhood on the west side of Los Angeles.

Nick Reiner did not resist when he was arrested hours later in the Exposition Park area near the University of Southern California, about 22.5 kilometres from the crime scene, police said.

He had been expected to make an initial court appearance earlier Tuesday, but his attorney Alan Jackson said he was not brought from the jail to the courthouse for medical reasons and the appearance would not come before Wednesday.

Jackson is a high-profile lawyer who represented Harvey Weinstein at his Los Angeles trial and Karen Read at her trial in Massachusetts. He was a central figure in the HBO documentary on the Read case.

Rob Reiner was the Emmy-winning star of the sitcom "All in the Family" who went on to direct films including "When Harry Met Sally..." and "The Princess Bride".

He was an outspoken liberal activist for decades.

Michele Singer Reiner was a photographer, movie producer and advocate for LGBTQ+ rights.

They had been married for 36 years.

Representatives for the Reiner family did not respond to requests for comment. (AP)