Conan O'Brien "was in shock for quite a while after" Rob and Michele Reiner's deaths

Nick was later arrested charged with two counts of first-degree murder and Conan, 62, admitted he has struggled to come to terms with the tragedy.

He told The New Yorker: "I knew Rob and Michele, and then increasingly got closer and closer to them. We [he and his wife, Liza Powel O'Brien] were seeing them a lot.

"They were just such lovely people. And to have that experience of saying good night to somebody and having them leave and then find out the next day that they're gone... I think I was in shock for quite a while afterward. I mean, there's no other word for it.

"It's just so awful. And I think about how Rob felt about things that are happening in the country, how involved he was, how much he put himself out there - and to have that voice go quiet in an instant is still hard for me to comprehend."

Conan went on to praise 78-year-old Rob's work as a director - which included classics such as When Harry Met Sally, A Few Good Men, Spinal Tap and The Princess Bride.

He said: "It's an almost impossible feat [to make seven movies in roughly a decade] that are classics... With Spinal Tap alone, if that'd been the only thing he ever did, he influenced my generation enormously. Spinal Tap - when it came out, I was in college, and it was like a splitting-the-atom moment."

It was previously claimed that Rob and Nick reportedly got into a heated argument at Conan's party.

One source told PEOPLE: "Nick was freaking everyone out, acting crazy, kept asking people if they were famous."

Rob and his wife left the star-studded party following the argument, TMZ reported.

It was also reported that Nick remains alone in his cell at all times and is served three meals a day in confinement. He is reportedly not allowed to communicate with anyone other than his legal team and jail personnel.

A source told PEOPLE: "This is important so that no one compromises this high-profile case, and so that no civilian or inmate can ask him questions, such as why he killed his parents."