Rob Reiner Got Into 'Very Loud Argument' With Son Nick at Conan O'Brien's Christmas Party Hours Before His Brutal Murder

Rob Reiner and his son Nick were involved in a heated altercation at Conan O'Brien's Christmas party on Saturday night, December 13 — just hours before the famous film director and his wife Michele Singer Reiner, were found murdered inside of their Los Angeles home.

The Princess Bride director got into a "very loud argument" at the A-list bash, with their amplified conversation being vocalized enough for other guests to hear, family sources revealed to TMZ shortly after Nick was arrested in connection with his parents' brutal killings.

According to the insiders, Rob and Michele left O'Brien's gathering shortly after the explosive argument between the dad-of-four and his son, though it is unclear if Nick left at the same time or on his own accord.

The family sources spilled that Michele had grown tired of dealing with Nick's mental health issues in the months leading up to her death and complained to friends about her son's addiction struggles.

"We've tried everything," Michele reportedly told friends after recently hitting her breaking point with Nick.

As OK! previously reported, Rob and Michele were found dead in their Brentwood, Calif., mansion by their daughter Romy, who called police and warned them her brother Nick "should be a suspect" because he's "dangerous."

Nearly a decade before the tragedy unfolded, Rob and Nick worked on the 2015 film Being Charlie together, which the slain star directed and his son co-wrote.

The movie covered themes of substance abuse, rehab and family relationships — and was loosely based on Nick's own drug addiction struggles.

Nick entered 18 different rehabilitation facilities before becoming homeless. While promoting the film, his father opened up about the affect his son's addiction struggles had on him as a parent.

Noting he was "never angry" at Nick during an interview with People in 2016, Rob explained: "I felt bad for him and I didn’t know what to do to help – and a lot of times parents don’t know what to do."

The When Harry Met Sally actor had mixed feelings about shipping Nick away to rehab, admitting, "You kind of throw yourself at the mercy of a lot of people who are supposed experts. They’ll all tell you these things, but they don’t take into account your child. And you should know your child better than they do anyway. That is something I learned as we went along."