Inside the Biggest Bombshells From 'The Reiner Murders: What Really Happened' — As Investigators Attempt to Make Sense of the Violent Deaths of Famous Director and Wife

A new documentary pieces together chilling details behind the murders of director Rob Reiner and his wife, Michele Singer Reiner, including the alleged involvement of their troubled son Nick Reiner.

RadarOnline.com can reveal the seven biggest bombshells from the TMZ project.

In the latest episode of TMZ Investigates titled The Reiner Murders: What Really Happened, which aired on January 9, the news outlet shared how Nick's weight gain and changes to his schizophrenia medications may have driven him to commit the killings of Rob and Michele at their Los Angeles home on December 14, 2025.

According to sources, Nick was diagnosed with schizoaffective disorder in 2020. He had also been diagnosed with schizophrenia just weeks before his parents' deaths.

The medications he was taking for his mental illness allegedly made him "erratic and dangerous," said the insiders.

The documentary also disclosed how Nick consulted his doctor about his weight gain, which is a common side effect of the medications. The physician changed the pills, but his behavior reportedly became more alarming in the month before the murders.

"[Doctors] did not attempt to place Nick on a temporary psych hold to stabilize him," said a source.

A second insider said Nick is "not competent to stand trial" due to his condition.

Although Rob and Michele's drug addict son had trips to rehab, Nick had not reportedly been using illegal drugs "before everyone knew" he was suffering from schizoaffective disorder.

"So our sources have told us in the five-plus years since Nick was diagnosed… he has not been using illegal drugs," said TMZ supervising producer Olivia Heinle. "But the drugs that landed him in rehab were prescription pills."

In The Reiner Murders: What Really Happened, TMZ's executive producer Charles Latibeaudiere cited a source who claimed Rob and Michele were awake when they were murdered inside their Los Angeles home.

Commenting on Nick's mental state, 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."

Nick's rehab stints began when Rob and Michele found him "doing both Percocet and Xanax with a friend," per Heinle.

Charles added the Being Charlie co-writer met another drug addict while in rehab, learning it was "much easier to score heroin than prescription drugs."

"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," Dr. Drew Pinsky, an addiction specialist who has not treated Nick, told TMZ.

Micholas Matthews, CEO of Stillwater Behavioral Health, added, "The scariest thing about it is when you're altering your brain chemistry with illicit substances, i.e., you're abusing methamphetamine, you're abusing opiates… it can exacerbate your symptoms and make them exponentially worse."

TMZ founder Harvey Levin confirmed in the TMZ Investigates episode that a "critical piece of evidence" in the case has not been found.

"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," he added. "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."

Elsewhere in The Reiner Murders: What Really Happened, Rob's friend Bill Maher slammed Donald Trump's reaction to the killings.

"[But] I can say that about 1,000 things Donald Trump has done. It was kind of nice to see Republicans, not all of them, but quite a few, standing up and saying, 'Let's not do that. Really? You have to do that?'" he said.

Maher also mourned the loss, adding he lost "a friend and, just besides that, a great filmmaker."

"Rob definitely gave 'nepo baby' a good name. I loved his father. The Dick Van Dyke Show was the greatest sitcom ever. Rob was an A-list director on a level Carl Reiner never got to. Carl Reiner never had a string of movies like When Harry Met Sally, A Few Good Men, Princess Bride. He had a run that was A-list and varied," he continued.

Former reality TV star Alexis Haines also appeared in the documentary, during which she claimed the mental health system "failed" the Reiner family and that the medical professionals betrayed them "in a fatal way."

"People who are in active psychosis don't belong in a residential treatment center at first. They belong in a hospital. Without a shadow of a doubt, the mental health system in America has failed the Reiner family," she said. "There's no question that Nick should have been hospitalized during this period of time. He should have been contained and in a safe environment where he couldn't leave until his medications were adjusted until there was a noticeable difference in his affect and behavior."