Dramatic images show Nick Reiner being forced to the ground and handcuffed after the murder of his parents, Rob Reiner and Michele Singer Reiner. 

Nick, 32, was at a Los Angeles subway station in Exposition Park, 15 miles from his parents' Brentwood mansion when officers pounced on Sunday night. 

He was arrested by the LAPD’s robbery homicide division with the help of US Marshals, who pushed Nick in front of a squad car. 

Nick had earlier checked in to The Pierside Santa Monica, where staff later discovered a shower 'full of blood' and a trail leading off of his bed, as well as a window covered up by bedsheets.

He checked in at 4am, just hours after he and his parents had an intense argument at Conan O'Brien's holiday party, TMZ reported.

Witnesses said that Nick looked 'tweaked out' when he arrived and that he never checked out.

Rob, 78, and Michele, 70, were found knifed to death by their daughter at their $13.5 million Brentwood mansion on Sunday, with police now saying their son Nick is 'responsible' for their deaths. 

The death of the Reiners and the arrest of their son has shocked Hollywood and the family's many famous friends.

Nick, who is known to have a history of drug addiction and volatile mental health, is now facing federal murder charges and is being held without bail.

His arrest came after Romy reportedly told police that a family member 'should be a suspect' because they are 'dangerous'.

Just hours earlier, Nick had attended the holiday party at O'Brien's home with his parents, and reportedly left A-list guests concerned after they got into a 'very loud argument'.

'Nick was freaking everyone out, acting crazy, kept asking people if they were famous,' a source told PEOPLE about the bash.

The family had been dealing with Nick's spiraling mental illness and drug issues for months at that point, telling friends 'we've tried everything,' according to TMZ. 

Nick had even previously attended rehab when he was just about 15 years old.

By the time Nick was 22 in 2016, he said he had gone to rehab 17 times, adding that he had been left homeless after refusing to get help on multiple occasions.  

'If I wanted to do it my way and not go to the programs they were suggesting, then I had to be homeless,' he told People, seemingly referring to his family.

'I was homeless in Maine. I was homeless in New Jersey. I was homeless in Texas. I spent nights on the street. I spent weeks on the street. It was not fun.' 

Eventually, Nick said he 'got sick of it'. 

'I got sick of doing that s***. I come from a nice family. I'm not supposed to be out there on the streets and in homeless shelters doing all these f*****-up things.' 

One year prior, Nick's parents expressed regret at how they had dealt with their son's addiction, saying they failed to listen to him and instead relied on medical professionals to get him through it. 

'When Nick would tell us that it wasn't working for him, we wouldn't listen,' Reiner told the Los Angeles Times at the time.

'We were desperate and because the people had diplomas on their wall, we listened to them when we should have been listening to our son.'

Michele added: 'We were so influenced by these people. They would tell us he's a liar, that he was trying to manipulate us. And we believed them.'

Once Nick became sober, he and his father would go on to co-write the semi-autobiographical movie Being Charlie about his struggles with drug addiction and the impact it has on a person's family.

Nick worked on the film from rehab and collaborated with his director father on the project, which depicts the strained relationship between an actor father and his addict son and tracks closely with the Reiner family's own experience, they said at the time.

It ends with an apology from the father about the occasionally harsh way he treats his son, including enforced stints in rehab, something Reiner said he gave his son in real life.

In a 2016 interview with the BUILD series while promoting their film, Nick said that he 'didn't bond' well with his father when he was younger, and said that working on Being Charlie 'made me feel closer to him'.

He said at the time of Being Charlie's release that he hoped to stay off drugs so that he would never be homeless again.

'When I was out there, I could've died. It's all luck,' he said. 'You roll the dice and you hope you make it'.

Close friends Billy Crystal and his wife Janice rushed to the Reiner home to say their goodbyes moments after the couple were brutally murdered - reportedly arriving in time to see first responders tend to the bodies.

The couple were found dead by their daughter, Romy, who called the Crystals about the tragedy after reporting the murders to the police, TMZ reports.  

The publication noted that the couple 'wanted to say their goodbyes'.

When police then cordoned off the property, Crystal was seen appearing emotional as he walked arm-in-arm with his wife, holding his hands in his face and seemingly wiping tears from his eyes. 

Reiner is known for making many of the best-known movies of the 1980s and 1990s, including Stand By Me and The Princess Bride in 1987, legal thriller A Few Good Men in 1992 and romantic comedy When Harry Met Sally in 1989, starring Crystal.

The two had already had a decade-long friendship, as they first met on the set of classic sitcom All In The Family in 1975 when the two were cast as best friends.

In a column for The Hollywood Reporter in September 2016, Crystal remarked that their chemistry on screen was so palpable that they decided to be friends away from the camera.

Crystal wrote: 'It worked really well, and we said, "It feels right onstage, why don’t we just continue this in our lives?"

'We became the closest of friends. And when I moved out here, we just spent all kinds of time together.'

Of course, Reiner most famously directed him in the aforementioned 1989 classic film When Harry Met Sally, alongside Meg Ryan. 

Nora Ephron penned the memorable movie, which centered on two unlikely college acquaintances who move to Manhattan and embark on an on/off friendship spanning 11 years.

Crystal has previously said that one of his favorite moments in their friendship was at the first screening of When Harry Met Sally.

He wrote in the THR column: 'Rob and I were sitting in the back next to each other. Then the orgasm scene happens, and the place goes berserk. When Rob’s mother, Estelle, says, “I’ll have what she’s having,” it was thunderous, a laugh you can only hear with the best of jokes in a concert hall.

'It’s those moments that make movies so spectacular: You set up the joke in September, and you don’t hear the punch line until May. We just grabbed each other’s hands because we knew something exciting was about to happen with this movie.'

The Los Angeles Fire Department (LAFD) confirmed it was called to the couple's Brentwood home at about 3.30pm on Sunday and found a man and woman dead in the property.

Reiner's family have since said in a statement of the heartbreaking deaths: 'It is with profound sorrow that we announce the tragic passing of Michele and Rob Reiner. We are heartbroken by this sudden loss, and we ask for privacy during this unbelievably difficult time.'

The couple had posed for their final full family photo in September with Nick, Romy, and their eldest son Jake and his wife Maria Gilfillan at the premiere for Spinal Tap 2, which he directed and wrote.