The mourning over Michael Jackson's death may have subsided, but the investigation into the circumstances of his death has not. A source has told the Associated Press that Conrad Murray, Jacko's personal doctor, administered the powerful anesthetic Propofol the last night of his life. Authorities, who are in the process of carrying out a manslaughter investigation, suspect the drug was responsible for Jacko's sudden demise. Dr. Murray has said through his lawyers that he did not "prescribe or administer anything that should have killed Jackson." Whether Murray will face criminal charges—and what, if any, those charges will be—remains unclear.