Details on Adam Rich's final moments have come to light.

The Eight Is Enough actor died in January at age 54 due to an accidental fentanyl overdose, according to the L.A. County Medical Examiner's autopsy report obtained bt E! News. 

While his cause of death was attributed to the opioid, Rich also had non-toxic amounts of alcohol and lorazepam—a drug that treats anxiety—in his system at the time, per the report.

Law enforcement sources told TMZ in January that his body was discovered in his Los Angeles-area home.

Rich's rep Danny Deraney confirmed his cause of death to E! News, adding that the lorazepam was prescribed by his doctor and the star had not been using drugs "for quite some time." 

"If there is any silver lining, it's that our suspicions were correct that it was an accidental overdose from fentanyl and not recreational drugs," Deraney told E! News. "We hope this closes the chapter on any suspicions people had and now the family can have some privacy as we move forward."

Rich was born in Brooklyn, New York, and landed his first role in a 1976 episode of The Six Million Dollar Man when he was about 8 years old. The next year, he debuted on Eight Is Enough, playing his most well-known part—as youngest son Nicholas Bradford, who popularized the "pageboy" haircut—on the ABC show until its end in 1981. 

"Adam was simply a wonderful guy," Deraney wrote on Twitter after his death. "He was kind, generous and a warrior in the fight against mental illness. Adam did not have an ounce of ego. He was unselfish and always looked out for those he cared about. Which is why many people who grew up with him feel a part of their childhood gone, and sad today." 

The rep put it simply, "He really was America's Little Brother."

However, to actress Betty Buckley, he was her stepson—onscreen, at least.

"Adam Rich was a light and my young pal for the four seasons I was blessed to work with him on 'Eight Is Enough,'" the 75-year-old, who played Abby Bradford in the series, wrote on Instagram in January. "I adored him and loved working with him in our scenes together on the show. He was so sweet, funny, fresh and natural. He brought a lot of joy to all of us on the show and to our audiences."

Explaining that she had remained friends with Rich all of these years, Buckley continued, "His love and support have always meant a lot to me. I am shocked by the news... recent years Adam dedicated himself to providing inspiration for others with mental and emotional illness. I will miss him greatly."

The former child star also worked on the TV series Code Red, CBS Children's Mystery Theatre and Dungeons & Dragons in the 1980s. 

However, Rich struggled with substance use and was treated for drugs at the Betty Ford Center in Rancho Mirage, Calif. in 1988 and 1991, per the Associated Press. In 2021, Rich described himself on social media as a recovering drug addict and said he battles "treatment resistant depression."

"Both mental illnesses," he tweeted. "Both kind of a bitch without the negativity. Let's PLEASE finally put an end to the stigmas associated with these diseases!!!"