Nick Reiner, who had been battling intensifying schizophrenia, reportedly became increasingly unstable and threatening after a recent change in his psychiatric medication, according to sources close to the situation.

Insiders revealed to TMZ that Nick was under psychiatric care as his mental health deteriorated in the months leading up to the tragic deaths of his parents, renowned Hollywood figure Rob Reiner and his wife Michelle, who were found fatally stabbed on Sunday.

According to reports, Nick’s behavior had grown alarmingly unpredictable in recent times.

He had been receiving treatment at a specialized Los Angeles rehabilitation center that focuses on substance abuse, with a reported cost of $70,000 monthly.

In the weeks leading up to the alleged murders, a change in Nick’s medication is said to have exacerbated his erratic behavior, with one insider describing him as being “out of his head.”

On Saturday night, Nick was brought by his parents to a star-studded holiday party hosted by Conan O’Brien, as his concerned parents reportedly wanted to ‘keep an eye on him.’ 

Guests at the A-list packed holiday party said Nick displayed ‘antisocial behavior’ including staring at attendees, and he and Reiner reportedly had a loud argument at the bash.

Insiders told Rolling Stone that Reiner and his wife Michele Singer asked if they could bring Nick to the party due to fears over his mental state, and at one point witnesses said Nick got into a heated moment with comedian Bill Hader. 

Nick Reiner was suffering with worsening schizophrenia and became ‘erratic and dangerous’ when doctors changed his psych medication, insiders say

Hollywood legend Rob Reiner and his wife Michelle Singer were found stabbed to death in their mansion on Sunday 

Nick attended Conan’s star-studded party with his parents on Saturday night, before Reiner and Singer were found dead in their $13 million California mansion on Sunday. 

At the time of Nick’s arrest, his sister Romy, 28, who discovered their parents bodies, told investigators her brother ‘should be a suspect’ because he was ‘dangerous.’

The Daily Mail exclusively revealed following the alleged murders that those around Nick saw him as a ‘ticking time bomb.’

Sources said that Nick’s drug use spiraled out of control after his parents threatened to kick him out of their home.

The troubled 32-year-old had been living in his parents’ guesthouse in Los Angeles for the past five years – where his behavior had become increasingly erratic and frightening, insiders claimed.

‘Nick had been living in their guesthouse, the same one he destroyed more than once, but it had been like a revolving door all his adult life,’ a source close to Reiner told the Daily Mail on Monday. 

‘He would do meth and not sleep for days and then have outbursts, breaking things, punching walls.

‘He was a ticking time bomb. His drug use was getting worse and his parents wanted him out,’ claimed the friend.

Reiner was arrested by the LAPD’s robbery homicide division with the help of US Marshals on Sunday night (pictured) 

Nick, seen in September 2025, has long struggled with mental health issues and substance abuse and had been open about his numerous trips to rehab 

Romy Reiner, seen with her brother Nick, discovered their parents bodies, and told investigators her brother ‘should be a suspect’ because he was ‘dangerous’ 

According to the source, Nick, who was one of three children, frequently laughed off the destruction he caused during drug-fueled episodes.

‘He used to brag how he could get away with anything and took money from his parents for drugs and prostitutes.

‘He would talk about this stuff in meetings, but then stopped going because he said it was too cultish,’ the source claimed. ‘He laughed about destroying his parents’ guesthouse more than once. He was so nonchalant about it.’ 

Nick appeared in court for the first time on Wednesday, and was formally charged with the murders of his parents. 

He waived his right to enter a plea, and his next hearing will be on January 7.

Investigators are still piecing together the whereabouts of Nick following the death of his parents – whose slain bodies were found in the master bedroom of their Brentwood mansion.