Nick Reiner became homicidal after schizoaffective medication was changed

Nick Reinierhis nervous breakdown in the weeks leading up to the murder of his parents, Rob And Michelle Reineris directly related to a baffling decision by doctors to change the medications he was taking for his mental illness… sources with direct knowledge tell TMZ.

TMZ has a new documentary — “TMZ Investigates: The Reiner Murders: What Really Happened” — airs Friday at 8 PM ET on FOX and drops on HULU Saturday. We explain in the doc that Nick was diagnosed with schizoaffective disorder around 2020… a condition that manifests with symptoms of schizophrenia — including delusions, hallucinations and disorganized thinking — and symptoms of mood disorders — including mania and major depression.

Our sources say Nick was stable on his meds for schizoaffective disorder for a month before the murders…we’re told the meds were working fine. For some reason, his doctors decided to change the medications. Our sources won’t say why doctors made that decision… only that we would be shocked to learn the reason, which we are told makes no sense.

We’re told the change in medications sent Nick into a spiral. He became irritable, erratic and increasingly dangerous. Our sources say Rob and Michele were alarmed by what they saw, but didn’t know what to do.

Our sources say that Nick became completely detached from reality at the time of the murders. We’re told the doctors didn’t try to put Nick in a psychiatric prison while they tried to adjust the medications and stabilize him.

This, we are told, could be the crux of Nick’s defense: that doctors sent Nick down a path that left him legally insane. Under California law, a defendant does not have to show that he did not know the difference between right and wrong to use the insanity defense… only that he did not understand the nature and quality of his act.