Rob Reiner's drug addict son Nick reportedly had a squabble with actor Bill Hader at Conan O'Brien's Christmas party the evening before he allegedly stabbed his parents to death.

Nick, 32, was arrested on Monday, December 15, for apparently killing the When Harry Met Sally director and his wife, Michele, at their Brentwood mansion. The three had attended O'Brien's party the day prior to the incident, where they got into a loud fight.

Party Guests Were Uncomfortable With Nick's Presence

Source: MEGABill Hader and Nick Reiner got into a tiff at the holiday party.

According to an eyewitness, Nick interrupted Hader, 47, while he was having a conversation with another guest at the holiday bash.

Nick was stunned, standing there for a minute before "storming off," the onlooker told NBC News on December 16.

Other partygoers also seemed uneasy at Nick's demeanor, with one source saying they were "uncomfortable with his behavior."



Source: MEGANick, Rob and Michele got into a 'very loud argument' at Conan O'Brien's bash, a source revealed.

Another person told the outlet that Nick's parents "were upset and embarrassed about their son's behavior at the party and expressed worries about his health."Nick, Rob and Michele also got into a "very loud argument" at the party, with some reports speculating that Nick possibly was back on drugs and was refusing rehab."They had had an argument at Conan's holiday party, and Rob had been telling people that they're scared for Nick and scared that his mental state was deteriorating,'' a source told the New York Post.

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Nick's Drug Addiction Has Plagued Him Since His Teen Years

Source: MEGANick's sister Romy was the one to find their parents' dead bodies on Sunday.

The Being Charlie screenwriter abused substances for most of his life before entering rehab at the age of 15, and experiencing bouts of homelessness. Nick has been in 17 treatment facilities since he was a teenager."They had had an argument at Conan's holiday party, and Rob had been telling people that they're scared for Nick and scared that his mental state was deteriorating," the source noted. "Nick was supposedly off drugs.""I know [the parents] wanted him to get help, go to rehab, but he wanted to get help while at home - he did not want to get treatment at a facility," a friend of the Reiner family told the outlet.

Rob and Michele Reiner's Throats Were Slit

Source: MEGARob and Michele Reiner were very worried about Nick's drug problems for quite some time.

Rob and Michele died on December 14, with their 28-year-old daughter Romy being the one to find their bodies that Sunday afternoon at around 3:30 p.m. Their bodies were already in rigor mortis by the time Romy discovered them, a.k.a. they were dead for hours.

The couple was found in bed with their throats slit. It's believed they were sound asleep before the slayings occurred.