Nick Reiner entered a not guilty plea on Monday in a Los Angeles courtroom, where he stands accused of murdering his parents, acclaimed filmmaker Rob Reiner and his wife Michele.
The 32-year-old appeared gaunt and hunched over during the proceedings, dressed in brown prison clothing.
When asked whether he understood what was happening, Reiner responded with a faint whisper of "yes."
His head had been shaved, and he was observed scanning the packed courtroom as though searching for a familiar face, according to reports.
Rob Reiner and his wife Michele Singer | GETTYThis marked his third court appearance since being taken into custody following the killings.
Reiner faces two counts of first-degree murder with a special circumstance of multiple murders, meaning he could receive either life imprisonment without parole or the death penalty if found guilty.
Rob Reiner, the 78-year-old director behind beloved films such as This Is Spinal Tap, The Princess Bride, When Harry Met Sally and Stand By Me, was discovered alongside his 70-year-old wife in their Brentwood residence on December 14.
Their daughter Romy made the grim discovery at the family's £1.6 million property.
Nick Reiner pleaded not guilty
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According to the LA County medical examiner, both victims died from multiple sharp force injuries sustained inside a bedroom of their home.
Nick Reiner was apprehended in Los Angeles later that same day and has remained in custody without bail ever since.
Michele Singer Reiner had established herself as an actress, photographer and producer, founding Reiner Light, a photography agency and production company.
The couple's surviving children, Jake and Romy, described experiencing "unimaginable pain" following what they called a "horrific and devastating loss".
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Nick Reiner will appear in court again in April
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Following the brief three-minute hearing, LA County District Attorney Nathan Hochman spoke to journalists outside the courthouse.
He confirmed that prosecutors are still weighing whether to pursue capital punishment, describing the case as "death penalty eligible".
"We take the process in which we determine whether or not the death penalty should be sought extremely seriously.
"That goes through a very rigorous process," Mr Hochman stated.
Rob Reiner was an award-winning Hollywood director and actor | GETTYThe DA explained that his office would examine all mitigating and aggravating factors before reaching a decision.
Mr Hochman also noted that the bulk of evidence has been handed over to the defence team, with prosecutors now awaiting the coroner's report.
Reiner is scheduled to return to court on April 29.