Bill Hader was recently observed in public for the first time since reports surfaced of a heated exchange involving Nick Reiner, preceding the tragic deaths of Rob and Michele Reiner.

The former “Saturday Night Live” star appeared visibly tense while engrossed in an intense phone call in Los Angeles.

Dressed in a black hoodie paired with matching sweatpants and slide sandals, the comedian paced back and forth as he engaged in the conversation.

Attempts to reach Hader’s representative for comments were not immediately successful, as Page Six received no response.

According to NBC News, Nick Reiner was reportedly involved in a confrontation with Hader during Conan O’Brien’s annual Christmas party last Saturday. This altercation allegedly occurred shortly before Nick’s arrest in connection with his parents’ deaths, and it was also reported that a tense encounter took place between him and his parents that evening.

According to an insider for the news outlet, Hader explained to Nick, 32, that he was having a private conversation. Nick allegedly stood motionless and stared at Hader before “storming off.”

Insiders told The Post on Monday that Nick allegedly “freaked out” during an argument with the “When Harry Met Sally” director at O’Brien’s annual star-studded soirée.

“They had had an argument at Conan’s holiday party, and Rob had been telling people that they’re scared for Nick and scared that his mental state was deteriorating,” a family friend of the Reiners’ shared with The Post.

The insider further alleged that Nick was “badly addicted to a combo of opiates and heroin.”

The screenwriter is said to have had a years long history of drug use and violent behavior — once trashing his parents’ guest house during an admitted drug-fueled outburst.

Rob and Michele were discovered stabbed to death in their Brentwood, Los Angeles, mansion on Sunday afternoon.

The director was 78 and his wife was 70 when their daughter Romy, 27, found them at home with their throats split open, per sources for The Post.

Romy allegedly told officers that a “dangerous” relative “should be a suspect.” Nick was subsequently arrested on Sunday evening at a Metro station in downtown Los Angeles, with dramatic video footage of the moment being released on Tuesday.

Nick is being held without bail after being transferred from Parker Center Jail to Twin Towers correctional facility. According to sources for TMZ, he is on suicide watch.

Los Angeles County District Attorney Nathan Hochman and Police Chief Jim McDonnell held a press conference on Tuesday announcing that Nick will be charged with two counts of first-degree murder.

“Today I’m here to announce that our office will be filing charges against Nick Reiner, who is accused of killing his parents,” Hochman explained to reporters.

“These charges will be two counts of first-degree murder with a special circumstance of multiple murders. He also faces a special allegation that he personally used a dangerous and deadly weapon, that being a knife,” he continued.

Nick is undergoing the process of medical clearance and will be brought to court to be arraigned, and could face life in prison without the possibility of parole.

Hochman also shared that “no decision” has been made on a potential death penalty, but the Los Angeles County District Attorney’s Office will take the “thoughts and desires of the family into consideration” when deciding Nick’s fate.

Rob and Michele married in 1989 after meeting on the set of “When Harry Met Sally.”

In addition to Nick and Romy, the couple shares son Jack Reiner, 34. Rob also adopted daughter Tracey Reiner, 61, from his previous marriage to Penny Marshall, who died in 2018.