Rob Reiner and his son Nick Reiner got into a heated argument at a Saturday night holiday party the night before the director and his wife Michele Singer Reiner were killed on the afternoon of Sunday, Dec. 14, multiple sources at the party tell PEOPLE.

TMZ first reported on Monday that Reiner, 78, and his 32-year-old son got into a “very loud argument” at a Christmas party hosted by Conan O’Brien on Saturday night.

Two sources confirm to PEOPLE that Reiner and his son got into the argument at O’Brien’s party.

Rob Reiner attends the premiere of Vertical Entertainment's "Shock and Awe" at The London West Hollywood on July 9, 2018 in West Hollywood, California; Nick Reiner attends AOL Build Speaker Series at AOL Studios In New York on May 4, 2016 in New York City

Matt Winkelmeyer/Getty; Laura Cavanaugh/FilmMagic

One of the sources tells PEOPLE: “Nick was freaking everyone out, acting crazy, kept asking people if they were famous.”

Rob and Michele, 70, then reportedly left the party after the argument, according to TMZ.

The couple were found slain in their Los Angeles home on Sunday, Dec. 14. Sources previously told PEOPLE the couple was discovered by their daughter Romy.

The Los Angeles Fire Department was called to the Reiner home around 3:30 p.m. local time to provide medical aid. First responders discovered Rob and Michele.

Nick was later arrested and charged with murder, and he is now being held without bail.

Michele Singer Reiner, Rob Reiner at SNL50: The Homecoming Concert at Radio City Music Hall on February 14, 2025 in New York, New York.

Michele Reiner and Rob Reiner.John Nacion/Variety via Getty

The couple first met while Rob was directing When Harry Met Sally… and later married in 1989.

Rob and Michele had three children together: Jake, Nick, and Romy.

Nick has previously spoken out about his struggles with addiction and homelessness, beginning in his teens. Reiner’s middle child told PEOPLE in 2016 that he cycled in and out of rehab beginning around age 15. As his addiction escalated, Nick said he drifted farther from home and spent significant stretches homeless in multiple states.

The story behind his and his father’s 2015 film together, Being Charlie, was partly inspired by Nick’s younger years.

Rob Reiner and his son Nick Reiner

Rob Reiner and his son Nick Reiner.Rommel Demano/Getty

Rob was the director of a number of iconic films, including This Is Spinal Tap (1984), Stand By Me, The Princess Bride (1987), and A Few Good Men (1992), among others.

The son of legendary comedian Carl Reiner, Rob broke into Hollywood on the popular sitcom All in the Family.