Around 4:07 p.m. on Saturday, Harrison County dispatch in Corydon, Indiana, received a 911 call for an unresponsive female.
Now, authorities have said that Moran "likely succumbed to complications of stage 4 cancer".
Happy Days cast members and fans have been mourning the death of Erin Moran, who played Richie Cunningham's kid sister, Joanie, in both the original series and its short-lived spin-off, Joanie Loves Chachi.
In a statement obtained exclusively by Closer, the Harrison County Sheriff's Department and the Harrison County Coroner's Office ruled that Erin's cause of death was due to cancer.
"Standard toxicology tests were performed and the results are pending however no illegal narcotics were found at the residence", the statement added.
"Such sad sad news ..."
Moran landed her first big role on the children's adventure show Daktari when she was just 8. "I'll always choose to remember you on our show making scenes better, getting laughs and lighting up tv screens". But more recently, Moran had been living in a trailer park with her husband, where she acted as a caregiver for her mother-in-law.
Meanwhile, according to Page Six, the Happy Days actress refused help from fellow former child stars as her life spiraled out of control. The show premiered the same year she made her film debut opposite Debbie Reynolds in How Sweet It Is.
In 2012, Moran was one of the "Happy Days" actors who won money in a settlement with CBS over merchandising payments.
Her post-Happy Days credits include guest stints on The Love Boat and Murder, She Wrote. "I'm sorry if that's cold, but God gave you a brain, gave you the will to live and thrive, and you gotta take care of yourself".
In 2008, she appeared on VH1's reality show "Celebrity Fit Club".