US investigators probing the death of Michael Jackson decided not to file charges against seven doctors who treated him, authorities said.
The doctors were part of an investigation by California state attorney general Jerry Brown's Bureau of Narcotic Enforcement, spokeswoman Christine Gasparac said.
One doctor whose name was not released was referred to the California Medical Board for prescribing drugs to a Jackson alias, she said.
Candis Cohen, a board spokeswoman, declined to confirm the action, saying complaints and investigations were not public record.
Jackson's personal doctor, Conrad Murray, pleaded not guilty to felony involuntary manslaughter in the singer's death.
Authorities said Murray provided Jackson with a mix of sedatives, including a powerful anaesthetic that killed him.
Murray was not among the seven doctors involved in the state investigation.
Los Angeles police who investigated the death had asked state and federal investigators to look into the prescribing practices of doctors who previously treated the 50-year-old pop star.
The US federal Drug Enforcement Agency also stopped investigating the actions of any other Jackson doctors, agency spokeswoman Sarah Pullen said.
"I am very disappointed," said attorney Brian Oxman, who represents Michael Jackson's father Joe Jackson in a wrongful death lawsuit against Murray. "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."