Nick Reiner entered a not guilty plea to two counts of first-degree murder after being accused of fatally stabbing his parents, Rob Reiner and Michele Singer Reiner, late last year, but a legal expert said his defense team will still likely have an uphill battle if the case goes to trial. "The fact that Nick got into an argument with the victims a day before the murders at Conan O'Brien's Christmas party is fatal to any real defense in the case," former federal prosecutor Neama Rahmani, president of Los Angeles-based West Coast Trial Lawyers, told Us Weekly exclusively after the defendant's court appearance on Monday, February 23. Nick, 32, and his late father, 78, reportedly got into a heated verbal dispute at the star-studded holiday party the night before the director and his wife, 70, were killed on the afternoon of Sunday, December, 14, according to TMZ. The couple's bodies were found in their master bedroom around 12 hours later. Prosecutors believe that Nick stabbed his parents to death inside their Los Angeles home before fleeing the residence. L.A. DA Is 'Fully Confident' a Jury Will Convict Nick Reiner of Murder On Monday, Nick entered not guilty pleas to two counts of first-degree murder with special circumstances and was denied bail, also waiving his rights to a speedy trial. He wore a brown jumpsuit and had a shaved head with facial hair for his court appearance, during which he sat behind glass. If convicted, he could face the death penalty or life in prison without parole. Rob Reiner, Michele Singer Reiner. Eric Charbonneau/Getty Images for Netflix Rahmani said the argument that allegedly took place between Nick and his parents mere hours before the crime is "evidence of premeditation, which is what you need for first-degree murder with special circumstances under California law." "If you get into an argument with someone and you come back with a weapon, that's premeditation," Rahmani added. "That's what happened with the [2019] Nipsey Hussle murder case in Los Angeles." Rahmani was referring to how prosecutors handling the Nipsey Hussle criminal case proved that defendant Eric Holder Jr. made a deliberate choice between his initial argument with Hussle and shooting the rapper outside of his Marathon Clothing store in South Central Los Angeles. (Holder Jr. was found guilty of first-degree murder in July 2022 and was later sentenced to 60 years to life in state prison.) Rob Reiner's Son Nick Seen in New Video Footage Just Before His Arrest The former federal prosecutor said that Nick's defense team may have a few potential strategies going forward, all of which could come with complications. "If you're analyzing defenses, one possibility is not guilty by reason of insanity. For that, you have to be unable to know right from wrong. If you're capable enough to have an argument with your parents at a Christmas party, you are not insane," Rahmani explained to Us. "He can argue self-defense, but his parents are a lot older than him and it's very difficult to prove self-defense unless they had some sort of weapon," Rahmani added, noting Nick's legal team may also take the route of claiming it was a crime of passion. However, Rahmani claimed "when you get into an argument the night before and you come back the next day with a knife, that's too much time for a heat of passion manslaughter defense." As for now, Nick will remain in prison with no bail.