Rob Reiner spoke candidly about his son Nick Reiner’s struggles with addiction in a 2015 appearance on The Late Show with Stephen Colbert—a conversation that has taken on new painful new resonance after Los Angeles police arrested the 32-year old for his alleged involvement in the deaths of his parents.

Reiner and his wife, Michele Singer Reiner, were found dead Sunday at their Brentwood home in what authorities are described as a double homicide. Police confirmed Monday that their adult son is the primary suspect. The investigation remains ongoing.

Reiner’s Late Show appearance came as he was promoting Being Charlie, a semi-autobiographical film he directed and co-wrote with his son. Reiner described the project as “the most personal film of anything I’ve done,” explaining that it was loosely based on Nick’s experiences with substance abuse as a teenager.

“He had some struggles from the time he was 15 to 19 with substances,” Reiner told Colbert, recalling multiple stints in rehab and calling it “a very tough time” for the family. Working together on the film, he said, was emotionally difficult—but ultimately meaningful.

“It was the most creative, most fulfilling experience I’ve ever had,” Reiner said, adding that the process forced both father and son to better understand what the other had been through.

During the interview, Reiner explained that he came to see addiction not as the core problem, but as a symptom of deeper distress. “My instinct was to really try to understand exactly what was causing his problems,” he said. “It’s not the taking of the drugs or the alcohol—it’s underneath that. You have emotional difficulties.”

“Taking drugs is like self-medicating,” Reiner continued. “You’re trying to feel better, make yourself feel better. So you have to try to understand what it is that’s causing the discomfort and the pain.”

Later in the conversation, Reiner reflected on the fear of parenting a child in crisis. “Your first charge as a parent is to keep your child safe,” he said, noting that he often relied on experts rather than trusting his own instincts.

At the time, Reiner told Colbert that his son had been sober for three years and was doing well, drawing applause from the studio audience.

Watch video of their full exchange at the top of this post.