Nick Reiner was acting strangely at Conan O'Brien's Christmas party, just hours before allegedly killing his parents. As we've been following, Rob and Michele Singer Reiner were heartbreakingly found dead on Sunday afternoon in their California home. Their 32-year-old son has been arrested for allegedly committing the killings. Previously, TMZ sources said Rob and Nick were caught getting into a "very loud argument" at the late-night star's holiday bash on Saturday night. Rob and Michele left shortly after. It wasn't immediately clear what the argument stemmed from or if Nick left afterwards, as well. But obviously, tensions were running high, and sources explained Michele had been telling her friends in recent months that the co-parents were struggling to figure out how to offer support to their son amid his battle with addiction and mental health issues, something he's dealt with since a teenager. They felt they'd exhausted all their options. So tough! Related: Zooey Deschanel's 'Heart Is Broken' Over Death Of New Girl Dad There's still so much left unknown about the director and film producer's final moments. But insiders are speaking out more about what happened at that Christmas party. On Monday, a source told Us Weekly that Nick was acting "creepily" at the party. The insider dished: "Nick was going up to people at Conan O'Brien's party, asking people if they were famous." Hmm. In other scenarios, it might seems innocent enough, right? Well, not for Hollywood. That kind of fame fishing is already considered a social faux pas for non-famous people, but for the son of a Hollywood director? Especially unusual! So, needless to say, it was actually rubbing a LOT of people the wrong way. Two sources for People also confirmed an argument occurred, with one detailing: "Nick was freaking everyone out, acting crazy, kept asking people if they were famous." Other sources told TMZ that the screenwriter seemed out of place at the formal shindig - both by how he was dressed and how he was acting. While everyone was dressed in nice suits and dresses, Nick showed up in a hoodie and and kept to himself most of the time, which many found odd. He was reserved and didn't interact with many as he roamed around the party, we guess aside from asking some if they were famous enough and arguing with his father. Sounds like things were really off, but there's still so much unknown... We'll keep you updated on any more updates as this tragic case continues to unfold. [Image via Michele Singer Reiner/Instagram & Nicky Nelson/WENN & NBC/YouTube] The post More Details About Nick Reiner's 'Crazy' Behavior At Conan O'Brien's Party The Night Before Rob & Michele's Murders appeared first on Perez Hilton.