Nick Reiner, the 32-year-old son of acclaimed filmmaker Rob Reiner, allegedly waited for an opportunity to attack his parents before killing them at their Los Angeles residence, according to a newly unsealed grand-jury indictment.
Reiner appeared in court on Wednesday and entered a not-guilty plea to two murder charges carrying a special-circumstance allegation.
The indictment, issued on 20 July, accuses him of committing the killings while lying in wait.
The latest filing enables prosecutors to bypass California’s preliminary hearing procedure and proceed towards trial.
However, it does not publicly outline what investigators believe Reiner did immediately before or during the alleged attacks.
Prosecutors described the case as an especially painful betrayal, saying the victims had loved and trusted the person now accused of taking their lives.
The lying-in-wait allegation could make Reiner eligible for capital punishment.
Although California currently has a moratorium on executions, prosecutors have yet to announce whether they intend to seek the death penalty.
Los Angeles County District Attorney Nathan Hochman said the grand-jury decision represents progress towards bringing the case before a trial court and securing justice for the victims.
Filmmaker Rob Reiner with Wife Michele Singer Reiner
Reiner is also accused of using a knife during the incident.
Under California law, the alleged use of a deadly weapon can serve as an additional aggravating circumstance.
The defendant is due back before a judge on 15 September.
He previously denied the original murder allegations in February.
Rob Reiner, 78, was widely recognised for directing and appearing in productions including This Is Spinal Tap, Misery and A Few Good Men.
His wife, photographer Michele Singer Reiner, 70, was also found dead at their Brentwood property on 14 December.
Authorities said both victims sustained several sharp-force wounds.
Their daughter reportedly discovered their bodies, while Nick Reiner was taken into custody in Los Angeles later that same day.
In April, the couple’s eldest son, Jake Reiner, described the devastating impact of losing both parents while his brother faced accusations in connection with their deaths.
Writing on Substack, Jake said the experience had left his life shattered, particularly because his brother was at the heart of the investigation into the killings.
By: Magdalene Agyeiwaa Sarpong