When Nick Reiner was photographed alongside his family at the Los Angeles premiere of his father’s comedy musical, “Spinal Tap II,” in September, he wasn’t smiling.

Instead, the son of legendary Hollywood director Rob Reiner and producer Michele Singer Reiner stood impassively for the family portrait alongside his siblings.

Three months later, Reiner, 32, has been arrested and deemed “responsible” for the deaths of his parents, Los Angeles police said in a Monday statement. He’s being held without bail.

Reiner was charged with two counts of first-degree murder in connection with his parents’ deaths, the Los Angeles County District Attorney’s Office announced Tuesday. He also faces a special allegation that he used a knife during the killings.

Reiner allegedly fatally stabbed his parents in the early morning hours of December 14, the DA’s office detailed in a news release.

The charges carry a maximum sentence of life in prison without possibility of parole or the death penalty. District Attorney Nathan Hochman said prosecutors have not decided whether they will seek the death penalty in the case.

Reiner is being represented by prominent defense attorney Alan Jackson, who told CNN on Tuesday that it wasn’t clear when his client would make his first court appearance.

While the news of the Reiners’ deaths sent shockwaves through Hollywood, it’s also placed renewed focus on Nick Reiner’s background and previous struggles with addiction. Here’s what we know:

Father and son were seen having an argument at a party

Nick Reiner was arrested Sunday night, police said, a few hours after his sister discovered their parents dead inside their family’s Brentwood home, according to police and a source familiar with the incident.

At the time of the killings, Reiner had been living with his parents in a guest house separate from the main structure, according to an individual close to the situation.

The night before, the couple and their son attended a holiday party at comedian Conan O’Brien’s home in Los Angeles.

During the party, Nick Reiner was seen having an argument with his father, a source familiar with the incident told CNN. It’s unclear what connection – if any – the argument may have had to the killings.

Reiner was taken into custody near the University of Southern California with help from the US Marshals Service and did not resist or try to run away, police said Tuesday.

Reiner was the middle of 3 children

Rob and Michele Reiner shared three biological children: eldest son, Jake; Nick, their middle child; and daughter, Romy, who was the youngest.

Rob Reiner also adopted and raised his ex-wife Penny Marshall’s daughter, Tracy. In comments to NBC News, Tracy said she was reeling from the news of her father’s death.

“I came from the greatest family ever,” she said. “I don’t know what to say. I’m in shock.”

The Reiners hail from Hollywood royalty. In the 1950s, comedian, actor and director Carl Reiner skyrocketed to fame on “The Dick Van Dyke Show.”

His son, Rob Reiner, became a household name in the 1970s for his role on the hit comedy “All in the Family” and later solidified his place as a Hollywood icon directing films such as “Stand by Me,” “When Harry Met Sally” and “A Few Good Men.”

But behind closed doors, the family – like many Americans – struggled to help their son, Nick, navigate his battle with addiction.

Reiner was candid about addiction struggles

Nick Reiner has previously said he’s done numerous stints in rehab and at times been homeless. He’s also spoken about arguments he had with his parents while in the throes of addiction.

Reiner’s mental health could come up during upcoming hearings on the case, Hochman said.

In a 2018 episode of “Dopey,” a podcast about the winding journey between addiction and recovery, Reiner said he first entered rehab when he was 15 and over the years learned to work the system.

“I just was like, ‘You know what, I want to go home,’ and so I just stayed sober long enough ‘til I could go home and then yeah, I just went home and did (drugs),” Reiner said in the podcast.

He also told the hosts about an outburst he had after he was “sequestered” in his parents’ guest house, which led to an argument.

“I got totally spun out on uppers, I think it was coke and something else, and I was up for days on end, and I started punching out different things in my guest house,” Reiner said.

“I think I started with the TV and then I went over to the lamp and then … just everything in the guest house got wrecked.”

Reiner said the outburst ultimately led to another stint in rehab.

‘Being Charlie’

In 2015, Nick Reiner co-wrote the film “Being Charlie,” a movie loosely inspired by his experiences with addiction and directed by his father.

During the promotional tour for the film, Nick Reiner often appeared alongside his father to discuss how he used his own experiences to inform the film.

“That made me who I am now, having to deal with that stuff,” he told People magazine in 2016.

During a joint appearance on AOL’s speaker series, “Build,” Reiner said he went through “a lot of dark years” as he fought through addiction.

But, he said he learned to use comedy as a way of coping with some of his experiences in rehab, and later, he channeled it into the film.

Rehab is “tragic and all but the people that are there are not going to want you to throw them a pity party. They’re going to want you to laugh at the situation and make light of it,” he said.

During the same interview, Rob Reiner called the project “the most personal thing I’ve ever done” and talked about working with his son.

“You don’t set out to have a cathartic experience or be therapeutic in some way,” the elder Reiner said.

“The fact that we were dealing with things that Nick had gone through and how I had related to it and how his mother had related to it … it forced me to have to see more clearly and understand more deeply what Nick had gone through and I think it forced him to see things that I had experienced during this process.” (CNN)