Nick Reiner, the 32-year-old son of late director and actor Rob Reiner, had long struggled with behavioral challenges and drug addiction, according to former instructors and sources familiar with the family.

The younger Reiner was arrested last week on charges of murdering his parents, Rob and Michele Singer Reiner, in their Brentwood home.

Alanna Zabel, a longtime yoga instructor for the Reiner family in the early 2000s, told the Daily Mail that Nick frequently disrupted sessions at the family's Los Angeles residence.

"He interrupted pretty much all of [their] yoga sessions," Zabel said, describing outbursts that could last "20 minutes or so" and involved "intense" screaming.

Nick's early years, Zabel said, were marked by high energy and persistent challenges in regulating his behavior. "This little boy had behavioral issues and was always upsetting everyone, but he was trying to figure it out," she explained.

Early Intervention and Efforts to Help

At the request of Rob and Michele, Zabel began working with Nick privately, attempting to channel his energy through physical exercises like handstands and crow poses. She told the outlet that she aimed to "exhaust him" to reach moments of mindfulness and connection, but "I rarely got there because he was just inexhaustible."

Zabel noted that his hyperactivity and intensity sometimes mirrored traits seen in children with attention-deficit/hyperactivity disorder (ADHD).

Children and teens with ADHD are statistically more likely to struggle with substance use, according to the Child Mind Institute.

Nick's long-standing battle with addiction has been documented publicly, including his co-writing of the semi-autobiographical film "Being Charlie," directed by Rob, which drew from his nearly 20 stints in rehab.

"There's also the fact that [the Reiners live] in Hollywood," Zabel said, reflecting on the pressures children of high-profile families face.

"I have witnessed the children of Hollywood personalities have a really difficult time...there's often a perception of negligence."

She added that easy access to drugs in major cities can compound these challenges if children lack the proper guidance.

Family Dynamics and Personal Struggles

An insider told Page Six that Nick "really resented his dad" and "hated himself for not being as talented, prolific or beloved as his dad or grandad."

Rob, 78, had an expansive 64-year career spanning 90 acting credits, 55 writing credits, 32 producing credits, and 30 directing credits.

His father, Carl, was also a legendary figure in entertainment, with a career spanning seven decades.

Zabel described Rob and Michele as "passionate people with very demanding lives" who "tackled [Nick's problems] head-on."

Despite their efforts, Nick reportedly developed an "egocentric mindset" and adopted "a negative perception" of his circumstances, she said.

Tragic Ending and Arrest

On Sunday, Dec. 8, Rob and Michele were found stabbed to death in their Brentwood home.

According to sources, the family's daughter, Romy, 28, discovered the bodies and indicated to responding officers that a relative "should be a suspect" because they were "dangerous."

Nick was subsequently arrested on murder charges and is being held without bail at Twin Towers Correctional Facility, the LA County Sheriff's Office confirmed.

The couple's other son, Jake, 34, described the loss as "unbelievably difficult" in a family statement. Rob and Michele had been married since 1989.

Rob is also survived by adopted stepdaughter Tracy, 61, from his first marriage to Penny Marshall.

Zabel, reflecting on her experience with Nick, has channeled some of it into writing her first children's book, A Chair in the Air, which follows a boy named "Nicky" who is "full of big feelings and even bigger energy."

She emphasized the importance of parental attention, advising, "Make sure that you are present and grounded and giving proper attention."