Nick Reiner pestered A-listers at Conan O'Brien's holiday party with a series of bizarre questions just hours before he allegedly killed his own parents. 

The festive gathering of Hollywood celebrities turned sour when legendary director Rob Reiner's 32-year-old son was asked to leave after badgering numerous partygoers with a series of inane queries.

'What's your name? What's your last name? Are you famous?' Nick Reiner asked, according to The Wall Street Journal. 

Nick was introduced to Bill Hader by his father and he proceeded to interrupt the SNL comedian. He then allegedly became irate when Hader responded that he was 'in the middle of a private conversation'.

'Nick just stood there and stared before storming off,' an insider previously told NBC News. 

Less than 24 hours later, Rob and Michele Singer Reiner were found stabbed to death inside their $13.5 million Los Angeles mansion, the Daily Mail previously revealed. 

A massage therapist arrived at the home for a scheduled appointment and was unable to get inside. The masseuse called the couple's daughter, Romy, who lives across the street, for help.

Romy was able to get the door open and discovered the gruesome scene of her father's lifeless body before fleeing from the home. 

The daughter had her roommate call 911 while she reached out to her father's longtime friend Billy Crystal. 

Romy only learned that her mother was also dead inside the house when paramedics arrived and broke the grim news, according to The New York Times.

Nick was ultimately arrested in connection with the murders later that day. He has since been charged with two counts of first-degree murder, and if convicted, could face life in prison without the possibility of parole or even the death penalty. 

Los Angeles County District Attorney Nathan Hochman said at a press conference Tuesday that the two were killed in the 'early morning hours' on Sunday. 

A source close to the investigation told the Daily Mail that they were found in bed Sunday afternoon with their throats cut and may have been asleep when they were murdered.

The Reiners had already been dead for hours when they were discovered, with their bodies showing signs of rigor mortis - which usually sets in between two to six hours after death, sources told TMZ.

'[Nick] could have done it not long after they all went home, meaning he went there and slit their throats in the middle of the night,' the Daily Mail source said. 'They were in bed when that happened.' 

The Los Angeles Fire Department has said first responders were called to the Reiner home around 3.30pm on Sunday and tried to render aid to the stabbed couple, to no avail. 

Romy then reportedly told authorities at the scene that her brother lived on the property as well, but investigators did not find Nick inside the guest house.

Instead, Nick had checked into The Pierside Santa Monica at 4am using his own credit card, when witnesses said he looked 'tweaked out,' TMZ reported.

There, staff are said to have discovered a shower 'full of blood' and a trail leading off of his bed, as well as a window covered up by bedsheets.

Nick had not yet checked out of the hotel by the time he was taken into custody at a Los Angeles subway station in Exposition Park, 15 miles from his parents' Brentwood mansion, at around 9.15pm.

Video exclusively obtained by the Daily Mail of the arrest shows how police cars with flashing lights descended on a busy intersection in downtown Los Angeles.

Nick could be seen in the footage walking slowly down the road before raising his arms in surrender as he was circled by cops.

Describing the scene, a witness told the Daily Mail how he saw five unmarked police cars surround Nick, who appeared to remain calm as armed homicide officers and US Marshals approached and slammed him to the ground.

'He didn't see them coming,' said bystander Kevin Cheatham, 34, adding that Nick appeared to remain 'cool' and calm. 

'I'm assuming they caught him surprised. He wasn't attacked, he was approached. He was minding his own business,' the witness said.

Nick has now been placed on suicide watch at the Twin Towers Correctional Facility, where he is being held without bail, a law enforcement insider told the Daily Mail.

He is expected to make his first court appearance this week, after his lawyer said he was not medically cleared for an arraignment on Tuesday.

In the meantime, a motive for the grisly double homicide remains unclear, as authorities announced Tuesday that there was no indication that Nick was under the influence of any drugs at the time of his parents' murders despite his history of substance abuse.

Nick had been to rehab 17 different times by the age of 22, after his family gave him the ultimatum of entering rehab or living on the streets, he once told People.

At times, though, he said, he chose the latter option. 

'If I wanted to do it my way and not go to the programs they were suggesting, then I had to be homeless,' Nick said. 'I spent nights on the street. I spent weeks on the street. It was not fun.'

Nick said that he had experienced homelessness in states including Texas, New Jersey and Maine.

When Nick then became sober, he and his father explored their complicated relationship in the 2016 film Being Charlie, in which the titular character deals with drug abuse.

Rob Reiner told the AP in a 2016 interview that making the motion picture with Nick 'forced us to understand ourselves better than we had.'

The filmmaker added, 'I told Nick while we were making it, I said, "You know it doesn’t matter, whatever happens to this thing, we won already. This has already been good." We've worked through a lot of stuff.'

But it has been said that Nick was once again struggling with drug abuse in recent weeks - and that Rob and Michele decided to bring their son to O'Brien's holiday party to 'keep an eye on him'. 

Nick is now facing two counts of first degree murder and 'a special allegation that he personally used a dangerous weapon,' LA County District Attorney Nathan Hochman said at a news conference on Tuesday. 

He noted that 'prosecuting these cases involving family members are some of the most challenging and heart-wrenching cases that this office faces because of the intimate and often brutal nature of the crimes involved.'

'Rob Reiner was one of the greatest filmmakers of his generation. His murder and his wife of more than 35 years, Michele Singer Reiner’s murder, are shocking and tragic,' the district attorney added.

'We owe it to their memory to pursue justice and accountability for the lives that were taken.'