Conan O'Brien Threw a Holiday Party to Forget a Bad Year. Then Nick Reiner Arrived. [View all]

Apparently there was a public confrontation prior to the murders.

https://archive.is/tu3kQ

Nick’s name was not on the invitation. But his parents asked O’Brien if he could tag along. His behavior, which had often been extreme and stressful, had grown degrees even more concerning in recent weeks. They were reluctant to leave him home alone, in the guesthouse of their Brentwood home, where he was currently living under their watchful supervision.

Hader calmly responded to Nick that he was engaged in a private conversation, according to someone with knowledge of the situation. Nick glared at him for what felt like an uncomfortable amount of time.

Some time later, shouts echoed. All conversations stopped and turned toward the racket. Two men, arguing. It was Rob and his son, having it out over Nick’s asocial and unsettling behavior.

Minutes later, the Reiners, mortified, apologized to O’Brien and left the party. It has not been determined if Nick left with them. The conversational din returned to the room, but the mood of the evening was altered.

At 4 a.m., Nick checked into the Pierside Santa Monica, where staff later discovered a shower “full of blood” and bedsheets hanging over the window.