Rob Reiner and wife Michele were apparently at their limit when it came to their son Nick's drug problems.

The couple was murdered at their Los Angeles mansion on December 14 - allegedly by Nick - following a "very loud argument" the three had at Conan O'Brien's holiday party the evening prior.

According to a source, the filmmaker and his wife were reportedly flummoxed over their son's issues and didn't know where else to turn to shortly before they were killed.

Rob and Michele 'Didn't Know What to Do' About Nick's Issues

Source: @michelereiner/InstagramNick has been in and out of rehab facilities ever since he was 15.

"Michele had been anguishing to friends over the last few months that she and Rob were at their wits' end over Nick's mental illness and alleged substance abuse issues," an insider told TMZ."They did not know what to do with their son Nick, saying, 'We've tried everything,'" the source went on.

Nick had been in and out of rehab facilities ever since he was 15, also experiencing homelessness across states such as Maine, New Jersey and Texas.

Rob and Nick's Film 'Being Charlie' Bonded Them

Source: @michelereiner/InstagramRob once got candid about the struggles of dealing with Nick's problems.

Nick even co-created his semi-autobiographical film, Being Charlie, with Rob, which chronicled his drug addiction issues.

The Stand By Me director had tried to help his son heal and recover over the years. Rob got candid about the struggles of dealing with Nick's problems, saying he was "desperate" to get him help."When Nick would tell us that it wasn't working for him, we wouldn't listen," he once told the Los Angeles Times. "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."

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Source: @michelereiner/InstagramNick also experienced homelessness across states such as Maine, New Jersey and Texas.

"We were so influenced by these people," Michele also explained to the publication. "They would tell us he's a liar, that he was trying to manipulate us. And we believed them."Rob also described Being Charlie as "cathartic" and "therapeutic" for him as the production helped him get closer to Nick.

After the drama was released, Nick looked back at his addiction battles, saying that he went through "a lot of dark years" while he was struggling."When I was out there, I could've died. It's all luck. You roll the dice and you hope you make it," he said in 2016.

Nick Was Arrested for Murder Shortly After His Parents' Deaths

Source: MEGANick and his parents got into a heated fight before he allegedly murdered them.

Nick was arrested for murder on December 15 after being questioned by the LAPD. Rob and Michele's daughter Romy was the one who reportedly found their bodies at their residence and called for medical help around 3:30 pm on Sunday.

Another source reported that Nick was acting erratically at Conan's Christmas bash."Nick was freaking everyone out, acting crazy, kept asking people if they were famous," the insider told People.