Authorities are questioning the reason why former "That ‘70s Show" star, Lisa Robin Kelly, 43, died in her sleep on Aug. 14 at a rehab facility in California, according to TMZ. The site reports that the Los Angeles County Coroner and Sheriff are conducting separate investigations while waiting for the results of toxicology reports. Kelly's autopsy was reportedly completed Saturday, but a cause of death has not been determined. Although the Sheriff's office reportedly has a security hold on the case to prevent information from being made public, sources tell TMZ that the doctor at the rehab center told the coroner Kelly had died from an embolism, which apparently struck the coroner as odd because an embolism would not leave any visible signs on a body. Kelly was reportedly taking detox drugs at the time of her death; the toxicology report is expected to indicate whether those drugs contributed to her heart stopping.