Children of slain Hollywood director Rob Reiner and his wife, Michele Reiner are speaking out for the first time after their deaths and the arrest of their brother, Nick.

Jake and Romy Reiner said in a statement on Wednesday that they are experiencing "unimaginable pain" after the "horrific and devastating loss". They did not directly address the allegations against their brother.

Nick Reiner, 32, appeared in court for the first time on Wednesday and waived his right to enter a plea to two charges of first-degree murder.

The couple were found dead on Sunday in their Los Angeles home. The county's medical examiner on Wednesday said they died in a homicide by multiple sharp force injuries.

Nick Reiner was taken into custody on Sunday and charged with murder on Tuesday.

"The horrific and devastating loss of our parents, Rob and Michele Reiner, is something that no one should ever experience," Romy and Jake Reiner said in a statement provided to CBS News, the BBC's US media partner. "They weren't just our parents; they were our best friends."

"We are grateful for the outpouring of condolences, kindness, and support we have received not only from family and friends but people from all walks of life," they added.

The siblings also asked for privacy "and for our parents to be remembered for the incredible lives they lived and the love they gave".

Family representatives did not immediately respond to the BBC's request for comment.

At the hearing in downtown Los Angeles on Wednesday, prosecutors and Mr Reiner's defence team agreed to delay his arraignment until 7 January, when he will once again have the opportunity to enter a plea.

As he appeared in court, Mr Reiner said only "yes, your honour" when asked by Judge Theresa McGonigle if he understood that he has the right to a speedy trial.

The judge earlier ordered the assembled media - who gathered outside the courthouse hours prior to the hearing - not to film the defendant, who was wearing a jail suicide-prevention smock.

Media inside the courtroom could not see Mr Reiner during the brief hearing because he was sitting in a corner out of sight, but glimpses afterward revealed his face was blank, and his arms bare and shackled.

He was initially slated to make a court appearance on Tuesday but had not been medically cleared to do so, his lawyer and prosecutors said.

His lawyer, Alan Jackson, told reporters outside court that there were "complex and serious issues" in the case that needed to be worked through in the coming weeks.

"We ask that during this process, you allow the system to move forward in the way that it was designed to move forward," Mr Jackson told reporters.

"Not with a rush to judgement, not with jumping to conclusions, but with restraint and with dignity, and with the respect that this system and this process deserves, and that the family deserves," he said.

The delay in Mr Reiner entering a plea could be designed to allow time for a psychiatric evaluation, one criminal defence lawyer told the BBC after the hearing.

"The psychiatric evaluation is generally done before arraignment to see if he is even fit to stand trial," Seth Zuckerman said.

Until the next hearing on 7 January, Mr Reiner will remain in custody at the Twin Towers Correctional Facility in Los Angeles.

If he pleads not guilty, he could be sentenced to life without the possibility of parole or the death penalty if convicted. Prosecutors have said no decision has been made yet about whether the death penalty will be pursued.

Rob Reiner directed a handful of iconic films in a variety of genres, including This is Spinal Tap, Misery and A Few Good Men.

Michele Singer Reiner was an actress, photographer and producer, and the founder of Reiner Light, a photography agency and production company.

"This case is heartbreaking and deeply personal, not only for the Reiner family and their loved ones, but for the entire city," LA Police Department chief Jim McDonnell said. (BBC)

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