Lisa Robin Kelly has died aged 43 at a Californian rehab facility, it has been confirmed.
The That '70 Show actress is believed to have suffered a cardiac arrest and passed away on Wednesday after attempts to revive her failed.
Lisa, who endured a long struggle with alcohol addiction, checked herself into a treatment centre on Monday determined to clean herself up, according to her agent.
Her spokesman confirmed to TMZ on Thursday: 'She had been fighting demons for a while and finally lost her battle.'Tragic end: Actress Lisa Robin Kelly reportedly passed away of cardiac arrest in a California rehab facility on Wednesday night after checking herself in voluntarily earlier that week
The way they were: The vivacious blonde starred as Eric Forman's promiscuous sister, Laurie, in That '70s Show between 1998 and 2003
Lisa was brought to the rehab facility by her new boyfriend on Monday, the website reported.
But just two days later, emergency responders were called when the actress was found unresponsive with needle marks on both arms.
Her new boyfriend - whose identity is not known - claimed the needle marks were not drug-related but were caused by multiple attempts to draw blood after she was hospitalised on Sunday with a blood alcohol level of .
Lisa's manager, Craig Wyckoff, told FOX411 he had spoken with the troubled star on Monday and she was 'hopeful and confident, looking forward to putting this part of her life behind her'.
The start of her troubles: Lisa is seen here in her mugshot after being arrested for drunk driving in Mecklenburg County, North Carolina in December 2010
