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Nick Reiner was diagnosed with schizophrenia, and in the weeks leading up to the murder of his parents, Rob and Michele Reiner, the meds he was taking made him "erratic and dangerous" ... TMZ has learned.

Two sources with direct knowledge tell TMZ ... Nick was under the care of a psychiatrist for mental illness. We're told in the month before the murders, Nick's behavior had gotten "alarming."

He had recently received care at a Los Angeles-based rehab facility that specializes in mental illness and substance abuse. We're told the facility charges $70,000 a month ... and lots of rich, powerful parents send their troubled kids there.

Our sources say 3 to 4 weeks before the murders, doctors changed his meds and he became even more erratic. Our sources say doctors were trying to adjust the medications so Nick stabilized, but it wasn't working.

Top Dawg Entertainment's annual Christmas Concert was once again the talk of the city of Watts with plenty of gifts and cheers being distributed ... and performances from several of the biggest artists, EVER!!!

TMZ Hip Hop was live and direct inside the renowned Nickerson Gardens housing projects once again to take in the festivities, which included blockbuster performances.

Kendrick Lamar and SZA shut down the evening, Dr. Dre and Snoop Dogg spread "California Love," and R&B sensation Mario performed "Let Me Love You."

JB Smoove is reflecting on Rob Reiner's life and work ... saying they’d been planning to link up for a while, but now JB's left with a meetup that never happened, and a moment he’ll always regret.

TMZ caught up with JB at LAX Thursday, and he tells us Rob had veganism on the brain and was planning to hit him up for advice ... but sadly, that conversation never got the chance to happen in person.

You gotta catch the clip -- JB also reflects on how Rob basically saved "Seinfeld," which of course led to the later success of "Curb Your Enthusiasm." And JB reminds us about those rare moments we miss when we let our day-to-day busy lives get in the way of deeper connections.

The "Ghost Adventures" episode featuring Weezer bassist Scott Shriner’s ex-wife, Jillian, is about to air ... and TMZ’s got the chilling first look, giving a pretty unsettling peek into her headspace before that wild run-in with cops earlier this year.

Have a look -- Zak Bagans says things took a seriously dark turn after Jillian gifted him serial killer Samuel Little's ashes, along with hand-drawn portraits of his victims that he’d left her in his will after she once wrote a book about him.

Nancy Grace says the double homicides of Rob Reiner and Michele Singer Reiner are a textbook example of a case that calls for the death penalty ... and that could be bad news for alleged murderer Nick Reiner.

Nancy tells TMZ ... this case is the classic example of when capital punishment should be applied, but that doesn't mean it's going to happen.

Los Angeles District Attorney Nathan Hochman mentioned the death penalty in a recent press conference, so it's being talked about among prosecutors ... but as Nancy explains, a final decision on capital punishment goes way beyond the D.A. office.

New footage shows Nick Reiner walking around in Santa Monica hours before his parents' dead bodies were discovered in their Brentwood home ... and he's heading toward the hotel he checked into.

TMZ obtained surveillance video from a local business on Santa Monica Pier. You see Nick walking down the sidewalk, towards the Pierside Santa Monica hotel.

The video was shot around 4 AM Sunday ... and Nick looks like he's carrying a black backpack and wearing a hat ... just like the video we obtained of him at a Brentwood gas station earlier in the evening.

We don’t know if this video of Nick was shot before or after he allegedly murdered his parents.

What we do know is that he checked into the hotel approximately 6 minutes after he's seen in this footage. Sources with direct knowledge told us no one saw any blood on Nick when he arrived at the hotel at 4:15 AM.

Riley Keough was snapped out and about for the first time since a bombshell lawsuit allegation claiming she's the biological mother to John Travolta's youngest son ... and TMZ has the shots.

Check out the pics ... Riley seemed to be in good spirits, doting on her kids among Christmas lawn decorations. A nanny helps Riley rally the two children while they admire the gingerbread man, miniature reindeer and tiny sleigh on a front lawn.

Riley shares two kids with husband Ben Smith-Petersen -- daughter Tupelo, 3, and a second child, whose name has not been publicly disclosed, who was born earlier this year.

Kata Hay, a former contestant on "The Voice," has been arrested on a vehicular homicide warrant ... TMZ has learned.

The Goodlettsville Police Department in Tennessee tells TMZ she had a warrant out of Davidson County, TN ... and was picked up by authorities in Oklahoma early Wednesday morning. The Osage County Sheriff's Office in OK tells TMZ a deputy from their department arrested her in a residence in the county on the active Tennessee warrant.

She's currently being held at the Osage County Jail in Pawhuska, Oklahoma, and the sheriff's office tells us she will go before a district court judge Monday to sign a waiver of extradition.

12/20 -- 7:55 AM PT -- Corey Feldman's lawyer Neville L. Johnson tells TMZ ... Feldman had no involvement with the documentary and is currently looking into how the footage was obtained in the first place.

He's also denying Haim "molested" him ... saying that idea is a "sensationalized mischaracterization of the statements made in the film."

Corey Haim's mother is blasting Corey Feldman for claiming her son "molested" him back in the day ... she says Feldman is lying about her late son for attention.

Haim's mother, Judy Haim, tells TMZ ... shame on Feldman for "creating another lie to poison people's heads and keep himself relevant."

In a new documentary, "Corey Feldman vs. The World," Feldman claims Haim molested him when they were filming 1987's "The Lost Boys."

Haim died in 2010, and Judy points out her son is not here to defend himself against what she says are bogus claims from Feldman.

Ebro Darden's morning show exile from Hot 97 last week blindsided the entire Tri-State area ... including DJ Drewski, who found out about his coworker getting canned like everyone else -- on the internet!!!

TMZ Hip Hop caught up with Drewski outside Johnny Donovan's 9th annual Celebrity Christmas Party this week, which benefits Little Flower Children Services.

Drewski is thankful to still have a job this holiday season and was aware his station was making changes. Still, he thinks Hot 97 skimmed out on the HR protocol, giving everyone the heads up "Ebro in the Morning" had been canceled.

The woman made famous in a drunken San Francisco restaurant fiasco put up one helluva fight with staff before getting face-planted ... and she's only 5 feet tall, new dispatch audio reveals.

TMZ just obtained the audio from Broadcastify, which gives another window into what happened Saturday night ... when Shireen Afkari got into a battle with workers at Patxi's Pizza. Video gone viral shows a wasted Afkari getting tossed out of the joint with her boyfriend.

In the audio, the dispatcher describes Afkari as a 5-foot-tall woman in her late 20s or early 30s, trying to get physical with the bar staff. But, as you know from the video, Afkari didn't "try" to get physical -- the pint-sized patron went all WWE on the workers, even pulling the hair of one employee.

Popular streamer Zoe Spencer threw it back, down and all around in a viral-worthy twerk off onboard the TMZ Brunch Bus Sunday ... and lucky for you -- we got it all on camera!

Check out the video ... everybody was getting loose on the Hollywood tour, thanks to some shots and Zoe's incredible hosting abilities, which were displayed in full force.

Zoe made the passengers' day by livestreaming the event while the bus rapped along to Kendrick Lamar's "Not Like Us," and even threw in a freestyle or two.

While Zoe's only been streaming for about a year, she's a seasoned veteran when it comes to having a ball.

Late "Pulp Fiction" villain Peter Greene had injuries on his body when he was found dead in his New York City apartment last week ... and authorities are still trying to figure out what caused the injuries, and what led to his death.

Law enforcement sources tell TMZ ... the actor's body was found with "some injuries but it's undetermined what caused the injuries."

We're told the medical examiner is still trying to determine a cause and manner of death ... and at this point it remains unclear if Peter's death is the result of homicide, suicide, drugs, or something else.

''Teen Mom'' alum Jenelle Evans is basically a brand-new woman -- and we mean literally -- after undergoing a full-blown mommy makeover, with her before-and-after pics showing a jaw-dropping transformation.

Check it out ... just days before her 34th birthday, JE debuted her bangin' new bod, and we’re breaking down everything she had done -- starting with a full boob overhaul, swapping in some 400cc silicone implants.

Jenelle’s boob upgrade was paired with a full tummy tuck, repairing post-pregnancy abdominal muscle separation ... and docs also removed a whopping 4.8 pounds of excess skin to give her a snatched, sculpted waistline.

Jack Black's fully in the holiday spirit ... rattling off a Christmas carol for us in his typical hard-rocking voice in New York City!

We caught up with the actor and singer outside "The Drew Barrymore Show" Tuesday ... and we asked him what his least favorite holiday tradition is.

Either Jack didn't hear us, or he chose to stay positive and give us one of his favorites instead ... because he launches into the song with his usual enthusiasm and projection.

Nick Reiner did NOT get booted from his parents' house the night before Rob and Michele Reiner were murdered in the Brentwood home where they lived with their son ... TMZ has learned.

There has been speculation online Rob kicked Nick out of the house Saturday night after returning from Conan O'Brien's Christmas party.

A source with direct knowledge tells TMZ, Nick left on his own accord. We do not know the circumstances under which Nick decided to leave. TMZ broke the story he and Rob got into a heated argument at Conan's party ... but it’s unclear if the exchange continued back at the Reiner residence.

Our sources confirm … Nick was not mentally sound in the period of time leading up to the murders. A source with direct knowledge tells TMZ … Nick's mental instability went beyond consuming illegal substances. We're told prescription drugs "messed with his head."