Los Angeles, California - The son of movie director Rob Reiner pleaded not guilty to the fatal stabbing of both of his parents when he appeared in a Los Angeles court on Monday.

Nick Reiner faces two counts of first-degree murder over the double killing that sent shockwaves through Hollywood days before Christmas.

The 32-year-old was arrested on December 14 after the bodies of his filmmaker father and his mother, photographer Michele Singer Reiner, were discovered at their home in the upmarket Brentwood neighborhood of Los Angeles.

Prosecutors said 79-year-old Rob Reiner – who helmed huge hits including When Harry Met Sally and A Few Good Men – and his wife (70) were stabbed to death.

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Nick Reiner, who has a history of addiction and mental illness, appeared in a downtown courtroom where he was formally told what charges he faces and had his rights explained.

A plea of "not guilty" is common at this stage, regardless of what the defense later does.

Reiner, who remains in jail and has not been granted bail, was ordered to return to court on April 29. An arraignment would usually take place much sooner, but Reiner was unable to appear at the first scheduled attempt.

Another hearing last month was halted after the court heard that lawyer Alan Jackson was no longer representing Reiner. The judge appointed an attorney from the public defender's office in his stead.

Jackson, a high-profile attorney who has previously represented Hollywood clients including Harvey Weinstein and Kevin Spacey, told reporters he was "legally and ethically" barred from explaining why he had stepped back.

"Circumstances beyond our control, but more importantly, circumstances beyond Nick's control have dictated that, sadly, it's made it impossible for us to continue our representation of Nick," he said.

Jackson said he and his team remained committed to Reiner's best interests and had faith that the legal process would "reveal the true facts of the circumstances surrounding this case."

He added that, "pursuant to the law in California, Nick Reiner is not guilty of murder."

If convicted as charged, Reiner could face life in prison without parole, or the death penalty, although California does not routinely carry out capital punishment.

Los Angeles County District Attorney Nathan Hochman told reporters outside court his office would be examining the circumstances around the killings before making a decision on whether to ask for the death penalty if Reiner is convicted.