'That '70s Show' Star Lisa Robin Kelly Dies At 43 [VIDEO]

Lisa Robin Kelly, who once starred as That '70s Show, died Wednesday night in her sleep at the age of 43.

TMZ reported the death and said that the actress was in a California rehab center at the time of her passing. Her agent told the site that Kelly checked into rehab of her own free will last week. The star had battled substance abuse for many years and was arrested three times on related charges.

"She had been fighting demons for a while and finally lost her battle," the rep said.

Sources said that Kelly wanted to get sober after falling off the wagon because of troubles with her estranged husband, Robert Gilliam. In July, Gilliam was convicted of domestic battery and sentenced to three years probation. He had beaten her last May in order to gain money from her residuals. Kelly filed for divorce in July and was ready to move on with her life, but it is believed she went into cardiac arrest.

Sources also told the site that needle marks were found on the actress's arms. However, her boyfriend blamed that on a recent hospital stay and that nurses were trying to find a vain. She had been admitted with a blood alcohol level of .34.

An autopsy has been scheduled.

Watch a clip of Kelly on That 70's Show below.