The shocking events surrounding the murders of beloved director Rob Reiner and his wife, Michele Singer Reiner, were explored on the latest episode of TMZ Investigates. Airing on Fox Friday, January 9, Harvey Levin and his team looked into new theories and lingering mysteries about the stabbing deaths of the Reiners, which were allegedly perpetrated by their own son Nick Reiner in December 2025. The TMZ team shared new details about the case and Nick's mental health from their sources, as well as speaking to Rob's longtime friend Bill Maher and The Bling Ring's Alex Haines, who shared her insight after experiencing heroin addiction at 19 and becoming a convicted felon. Nick was not involved in the documentary and has not publicly acknowledged a mental health diagnosis. However, he has spoken about his struggles more broadly in the past, including on an August 2018 episode of the "Dopey" podcast, where he detailed trashing his parents' guest house in the midst of his addiction. What Did Nick Reiner Say to Bill Hader? Inside Their Christmas Party Exchange "It's not much of a story," Nick shared at the time."I got totally spun out on uppers - I think it was coke and something else - and I was up for days on end. I started punching out different things in my guest house." When asked if there was any thought process to destroying the guest house, Nick responded, "You're crazy. No logic." As of publication, Nick remains in custody on two charges of first degree murder for the fatal stabbing of his parents at their Brentwood, California, home on December 14, 2025, just mere hours after they'd all attended Conan O'Brien's Christmas party. Keep scrolling for a breakdown of TMZ Investigates: The Reiner Murders: What Really Happened. Rob and Michelle's Murder Weapon Hasn't Been Found Yet The documentary reported that the murder weapon used to kill Rob and Michelle has not yet been found by authorities, which could impact the case against Nick. (Nick has been charged with two counts of first-degree murder.) "Our sources say a critical piece of evidence in this case has not been found. The murder weapon," TMZ's Harvey Levin claimed in the documentary. "It is really important for the D.A., because if Nick had gone out and purchased a knife shortly before the murders, it would show premeditation. If he took a knife out of the kitchen, for example, that might show more spontaneity. But that knife is really important. We know the police have been looking for it. But we are told so far they haven't found it." Nick Was Allegedly Diagnosed With Schizoaffective Disorder in 2020 According to TMZ's sources, Nick was diagnosed with schizoaffective disorder and "before everyone knew Nick was suffering from schizoaffective disorder, he was using meth and that makes schizoaffective disorder even worse. And he had a violent outburst," Levin claimed in the documentary. The TMZ team alleged that the outburst involved "tearing up" his parents' house. Schizoaffective disorder is a combination of schizophrenia and mood disorder symptoms, that includes a "rollercoaster of emotions" like mania, hallucinations or delusions. "So our sources have told us in the five-plus years since Nick was diagnosed... he has not been using illegal drugs," including meth, heroin and cocaine, TMZ supervising producer Olivia Heinle said. "But the drugs that landed him in rehab were prescription pills." The TMZ team also spoke about how Nick's mental illness related to the murder charges. Levin said of how the case was shaping up when Nick was arrested, "The plan was [for him] to plead not guilty by reason of insanity and it all centers around Nick's profound mental illness." Referring to sources close to the family, TMZ's executive producer Charles Latibeaudiere added, "He knows he killed his parents but he doesn't understand why he's in jail. He's delusional. He thinks this is all a conspiracy against him." According to Latibeaudiere, Rob and Michele were awake when the attack happened, per TMZ's source. Nick's Experience in His Rehab Stints In the documentary, TMZ detailed Nick's alleged experience in rehab (which he previously admitted to entering 18 times). The documentary claimed that Nick would do 30-day stints to "get you clean and they let you out" but the stays weren't long enough to address underlying mental health issues. "His first rehab stint was when his parents found him doing both Percocet and Xanax with a friend," Heinle said. Dr. Drew Pinsky, an addiction specialist who is not Nick's doctor, told the outlet, "Thirty days for me seems almost meaningless for someone with Nick's history. What you would want to do is put him somewhere structured and custodial for a very long period of time, maybe permanently. And parents have a real difficult time coming to terms with that." Latibeaudiere claimed that while in rehab, Nick encountered other addicts that only resulted in him learning other drug securing methods. "When he was there for the first rehab