The former wrestling star, real name Joan Laurer, was discovered by friend in her Redondo Beach, California apartment on Wednesday – and she may have been dead for days, the Los Angeles County Department of Medical Examiner-Coroner tells PEOPLE. She was 45.
"Evidently either a friend or someone close to her hadn't talked to her since Sunday and they went over there and went in and found her deceased or unresponsive," Assistant Chief Coroner Ed Winter says. "Paramedics were called and she was pronounced at the scene."
The sad news comes as Dr. Drew, who treated Chyna on Celebrity Rehab with Dr. Drew in 2008, tells PEOPLE that he believes she succumbed to addiction.
"I am very sad for Joanie and her loved ones, but I am also terribly angry because I suspect addiction may have taken another life," Dr Drew says.
Winter, from the L.A. County coroner's office, said an exact time of death has yet to be established but investigators believe she died Sunday night or Monday. Chyna appears to have been active on social media on Monday morning.
Winter noted that Chyna's death is not being investigated as a suicide. The case was reported by Redondo Beach Police as a possible overdose. The autopsy is pending.
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Chyna had a history of battling substance abuse, including her Celebrity Rehab appearance following a season on The Surreal Life that featured her drinking heavily.
On Sunday, Chyna appeared optimistic in a YouTube video posted in the early morning hours.
Making a fruit smoothie, the athlete said, "How lucky am I?" after noting that she was "doing good."
"I've been having fun because I feel like I can express myself and talk to my friends," she said.