Nick Reiner's Santa Monica hotel room 'full of blood' amid Rob Reiner, Michele Reiner's deaths: TMZ

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Nick Reiner's hotel room found bloody: TMZ

Prosecutors charged Nick Reiner with first-degree murder in the stabbing deaths of his parents at their Brentwood home.

Prosecutors on Tuesday charged 32-year-old Nick Reiner with two counts of first-degree murder in the stabbing deaths of his parents, Rob and Michele Reiner, inside their Brentwood home.

Los Angeles County District Attorney Nathan Hochman announced the charges at a news conference, calling the case one of the most serious his office can bring. "We will commit ourselves to bringing their murder to justice," Hochman said.

Investigators allege Nick Reiner stabbed his parents to death, though authorities have not disclosed a motive or the exact time of the killings.

According to witnesses, Nick Reiner and his parents attended a holiday party at Conan O’Brien’s home the night before the bodies were discovered. Witnesses say a loud, heated argument broke out during the gathering. One witness told FOX 11 Nick had been acting oddly that night.

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Hours later, around 12:15 a.m., Reiner was reportedly seen walking alone near a gas station close to the family’s Brentwood residence.

TMZ reports that Reiner checked into a Santa Monica hotel around 4 a.m. Sunday with his own credit card and that hotel staff later found blood in his shower and on his mattress. Police have not publicly confirmed those details.

Sunday afternoon, the Reiners’ daughter, Romy Reiner, discovered her parents dead inside the home and called 911. About six hours later, Los Angeles police took Nick Reiner into custody near the University of Southern California campus without incident. He is being held without bail.

Nick Reiner has previously spoken publicly about struggles with substance abuse and mental health. His 2015 film "Being Charlie," directed by his father, was loosely based on his experiences with addiction and recovery.

Outside the family’s home Tuesday, defense attorney Alan Jackson declined to answer questions about his client’s mental state.

If convicted, Reiner faces a maximum sentence of life in prison without the possibility of parole or the death penalty, Hochman said.

Authorities said it remains unclear when the alleged killings occurred or how Reiner traveled from Brentwood to Santa Monica.

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