Nick Reiner is set to be formally charged with the murders of his parents

Nick was arrested in connection with the murders several hours after his parents were killed.

Nick is currently being held without bail at Los Angeles' Men's Central Jail. He was due to appear in court on Tuesday. However, he hasn't yet been medically cleared to appear in court, according to his attorney, Alan Jackson.

Rob and his son Nick reportedly got into a heated argument on Saturday night.

Nick was seen having a heated disagreement with his dad at a Christmas party hosted by Conan O'Brien, according to People.

One source told the publication: "Nick was freaking everyone out, acting crazy, kept asking people if they were famous."

Rob and his wife left the star-studded party following the argument, TMZ reported.

News of the argument emerged shortly after US President Donald Trump took to social media to react to the tragedy.

The billionaire businessman wrote on the Truth Social platform: "Rob Reiner, a tortured and struggling, but once very talented movie director and comedy star, has passed away, together with his wife, Michele, reportedly due to the anger he caused others through his massive, unyielding, and incurable affliction with a mind crippling disease known as TRUMP DERANGEMENT SYNDROME, sometimes referred to as TDS.

"He was known to have driven people CRAZY by his raging obsession of President Donald J. Trump, with his obvious paranoia reaching new heights as the Trump Administration surpassed all goals and expectations of greatness, and with the Golden Age of America upon us, perhaps like never before. May Rob and Michele rest in peace (sic)"