Rob and Michele Reiner 'Tried So Hard' with Son Nick but He 'Didn't Take the Help Seriously' (Exclusive Sources)

Rob and Michele Reiner tried in many ways to help troubled son Nick, but the 32-year-old — now charged with murder in connection with their deaths — didn't take the support seriously, according to insiders.

The "loving" parents "tried so hard already for years," a source tells PEOPLE.

Another insider adds, "At the end of the day, Nick didn’t take the help seriously. This was true for years and years. His issues were far, far out of his parents' control."

"Nick lied a lot. He was unreliable, but he was also convincing and intelligent," says the insider. "His family was empathetic to how much his struggles contributed to his behavior. They never lost hope in him, even when he was scaring them or making their lives harder."

On Sunday, Dec. 14, Rob, 78, and his wife Michele, 70, were found dead inside their Los Angeles home. Nick was arrested later that night and has since been charged with two counts of first-degree murder in connection with their deaths. Nick appeared in court Wednesday, Dec. 17, and his lawyer Alan Jackson declined to enter a plea for his client. His arraignment will continue Jan. 7.

Nick co-wrote the 2015 film Being Charlie that his dad directed, loosely based on his own experiences with addiction. While promoting the project at the time, Nick — who'd been in and out of rehabs over 18 times by age 22 — was candid about those "dark years" in interviews.

In one Los Angeles Times interview, Rob and Michele shared a regret they had about handling their son's addiction struggles.

"The program works for some people, but it can’t work for everybody,” Rob said at the time. “When Nick would tell us that it wasn’t working for him, we wouldn’t listen. We were desperate, and because the people had diplomas on their wall, we listened to them when we should have been listening to our son.”

Michele added, “We were so influenced by these people. They would tell us he’s a liar, that he was trying to manipulate us. And we believed them."

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The Reiners' children Jake, 34, and Romy, 28, spoke out in a statement shared Dec. 17, expressing the "unimaginable pain we are experiencing every moment of the day."

"The horrific and devastating loss of our parents," the siblings added, "is something that no one should ever experience. They weren't just our parents; they were our best friends."

Nick joined the family on the red carpet of Rob's Spinal Tap II premiere in Los Angeles held Sept. 9. In a September interview with NPR, Rob mentioned that Nick "hasn't been doing drugs for over six years." He added of his son, "He's in a really good place."

In PEOPLE's latest cover story, one insider close to the family said the Reiners "could never reach stability with Nick. They tried everything — giving him space, keeping him close — but his struggles are so deep." That insider added: "It’s just a parent’s worst nightmare. They were such lovely people and tried in every way to help their son."