Seven doctors who treated the late Michael Jackson will not be charged in the singer’s death. According to The Associated Press California officials said Wednesday (July 28) that they will not file charges against the doctors who were under scrutiny as part of an investigation launched by the state’s Bureau of Narcotic Enforcement.

Jackson passed away in June 2009 after suffering cardiac arrest. His personal doctor Conrad Murray — who was not one of the seven doctors included in the investigation — has been charged in his death and pleaded not guilty to involuntary manslaughter after allegedly giving the star the potent anesthetic propofol.

“I am very disappointed,” said Brian Oxman, an attorney for Michael Jackson’s father Joe Jackson. “The misuse of medications by Michael Jackson in the last years of his life was excessive and to fail to bring that to the public eye is ignoring reality.” Oxman is serving as Joe Jackson’s lawyer in a wrongful death suit against Murray.

Bureau spokesperson Christine Gasparac told the AP that one of the doctors who was under investigation was referred to the California Medical Board for prescribing drugs to one of Jackson’s aliases, however, a spokesperson for the board did not confirm the referral. A spokesperson for the Drug Enforcement Agency told the AP that it has also dropped its investigation into Jackson’s doctors.

Murray lawyer Ed Chernoff has maintained that the doctor did not administer a fatal dose of propofol and has suggested that either Jackson gave himself the anesthetic or another person may have supplied the late star with the dose. However, an anesthesia expert has said the possibility of Jackson administering the drug himself is unlikely.

A preliminary hearing in the Jackson manslaughter case is slated for August and Murray faces a sentence of up to four years in jail.