Multiple reports say comedian Conan O’Brien stopped his party guests from calling the police on Nick Reiner, who had apparently become agitated and combative during the Christmas Party at O’Brien’s home the night before film director Rob Reiner and his wife were stabbed to death in their own home.

The Reiner family attended O’Brien’s Christmas Party on Saturday, December 13 and the media were soon flooded with reports that Rob, his wife Michele, and troubled son Nick exploded in a loud argument that had other party goers “freaking out.”

The Reiners quickly abandoned the party and fled in embarrassment. But it now appears that the argument was heated enough that some of O’Brien’s guests wanted to call the police. O’Brien, though. urged them not to do so, according to the Daily Mail.

“They got in an argument, the father and son. It got so bad and loud someone wanted to call the police to report it,” the insider said, according to the paper — which cited more than one insider concerning the incident.

“But Conan stepped in and said, ‘it’s my house, my party, I’m not calling the police.’ He talked them out of calling the police,” the source added.

“When the s**t was hitting the fan, somebody said we need to call the police. The conversation was about getting this kid put into a mental-health hold,” another source said, adding, “Conan O’Brien stepped in and said, ‘no, I don’t want the police at my house.'”

The second insider called the argument between Rob and Nick “pretty intense.”

One of the sources added, “It must be gut-wrenching for Conan to learn that this is how things turned out. I’m sure that night is replaying for him over and over.”

Rob Reiner and his wife, Michele Singer, were found murdered in their Brentwood home less than a day later.

Rob himself reportedly told friends he had become “petrified” by his son and worried that Nick might “hurt” him or someone else.

“I’m petrified of [Nick]. I can’t believe I’m going to say this, but I’m afraid of my son. I think my own son can hurt me,” the source said that Rob told them at the party.

Nick had been living in the guest house on the Reiner family estate after apparently relapsing into substance abuse. The 35-year-old has been in and out of rehab sine he was a teen and reportedly had at least 18 stints in rehab, all to no avail.

It has also been reported that Nick had been in an increasingly agitated state after recent changes to his medications to treat schizophrenia. The meds supposedly had him “out of his head,” witnesses have said.

Nick is being held without bail pending his arraignment scheduled for Jan. 7.

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