Alan Jackson steps down as lawyer for Nick Reiner, who is accused of killing his mother and father in December.

The high-profile lawyer representing Nick Reiner, who allegedly killed his father, director Rob Reiner, and mother Michele Singer Reiner in December, has resigned.

The announcement that lawyer Alan Jackson would step down from the case means that the younger Reiner will, at least for the time being, be represented by a public defender provided by the state.

During a news conference on Wednesday, Jackson did not provide a reason for his departure, instead citing the legal and ethical reasons he could not provide more details.

“Circumstances beyond our control and, more importantly, circumstances beyond Nick’s control have dictated that, sadly, it’s made it impossible to continue our representation of Nick,” Jackson said.

He added that, after weeks of investigation, “what we’ve learned, and you can take this to the bank, is that pursuant to the laws of this state, pursuant to the law of California, Nick Reiner is not guilty of murder. Print that.”

Jackson did not elaborate.

The lawyer had first appeared in court to represent the 32-year-old suspect just days after Rob Reiner and his wife were found dead on December 14 in their home in the upscale Brentwood neighbourhood of Los Angeles, California.

The cause of death was determined to be “multiple sharp force injuries”, another term for stab wounds.

Jackson, whose past clients include producer Harvey Weinstein and actor Kevin Spacey, did not explain how he was hired or who hired him after Nick Reiner was arrested for the killings.

On Wednesday, Deputy Public Defender Kimberly Greene took over Nick Reiner’s defence in the case.

That came as the defendant, standing behind glass in a custody area of the courtroom and wearing brown jail garb and with his hair shaved, briefly appeared in a Los Angeles court, where he was meant to be arraigned and enter a plea to two charges of first-degree murder.

Instead, the arraignment was postponed to February 23.

“The Public Defender’s Office recognises what an unimaginable tragedy this is for the Reiner family and the Los Angeles community,” Deputy Los Angeles Public Defender Ricardo Garcia said in a statement following the hearing.

“Our hearts go out to the Reiner family as they navigate this difficult time. We ask for your patience and compassion as the case moves through the legal process.”

Rob Reiner’s killing resonated across the world, reflecting the global impact of his films, which included the coming-of-age drama Stand By Me, the courtroom thriller A Few Good Men and the romantic comedy When Harry Met Sally.

Rob and Nick Reiner had previously worked together on a film, Being Charlie, which was partially based on the younger Reiner’s struggles with drug addiction and mental health.