Rob Reiner and Son Nick ‘Got in a Big Fight’ at Conan O’Brien’s Party Hours Before Murders: ‘He Was Freaking Everyone Out’

Rob Reiner, 78, and his wife Michele, 68, were killed in the family’s Los Angeles home on Sunday afternoon, according to police

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Rob Reiner and Nick Reiner

NEED TO KNOW

Rob Reiner and his son Nick Reiner got into a “big fight” at a Christmas party hosted by Conan O’Brien on Saturday night, a source tells PEOPLE

Reiner and his wife Michele Singer Reiner were found slain at their home on Sunday afternoon

Nick was later arrested and charged with murder

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. One source says Nick was arguing with his father over money for a movie project.

“Rob wouldn’t agree to give him the money because he knows his son has a serious drug addiction and was lying about it,” the source says. “Rob was saying no, and they got in a big fight.”

Another source tells PEOPLE: “Nick was freaking everyone out, acting crazy, kept asking people if they were famous.”

Rob and Michele, 68, 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.

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Michele Reiner and Rob Reiner

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.

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Rob Reiner and his son Nick Reiner

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.