Nick Reiner 'almost childlike in jail' after parents' alleged murders, Fox Nation documentary reveals

A new "TMZ Investigates" special on Fox Nation claims Nick Reiner is in no mental state to stand trial for the alleged murders of his parents, Rob and Michele Reiner, as the program reveals new details about his mental state, medication changes and the case against him.

"He is not competent to stand trial right now. He is almost childlike in jail, we're told," TMZ executive producer Harvey Levin told "Fox & Friends" on Monday. 

"He can't process the consequences of what he's done. He knows what he did. He just can't understand where he is right now, and I know that sounds crazy, but he is out of his head right now."

Doctors had changed Nick's medication a month before the murders due to his complaints of weight gain, and that adjustment "messed Nick up," Levin said, explaining that Nick was diagnosed with schizoaffective disorder — which can cause delusions, hallucinations and mood disorders.

ROB REINER AND WIFE MURDERED: TIMELINE SHOWS ARGUMENT WITH SON NIGHT BEFORE DEATHS

Levin described the alleged murders as "incredibly brutal."

"We know people in the medical examiner's office who are traumatized just by the pictures," he said.

NICK REINER BELIEVES HE'S A VICTIM OF 'CONSPIRACY' WHILE IN JAIL FOR PARENTS' MURDERS: DOCUMENTARY

He claimed the killings had "all the markings of a meth murder" and that Nick had been using meth when he was "off the rails" after his medication switch-up, adding that he was arrested in a drug den.

"It has the markings of somebody who was just wild, wildly strong. We have not gotten the confirmation of that, but we've talked to people... If he were just Nick Reiner without something additional, the carnage wouldn't have been the way it was," Levin said.

Given the case shaping up against Nick, Levin also touched on why Alan Jackson, the high-profile attorney who previously represented Nick before stepping away from the case, maintains that he is not guilty.

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"[Jackson] says [Nick] is not guilty. What he's really saying is, not guilty by reason of insanity. And I think that's gonna be the plea in this case, because there's no way he'll plead not guilty."

To learn more about the grisly case that's rocked the nation, subscribe to Fox Nation and stream "TMZ Investigates the Reiner Murders: What Really Happened."