Los Angeles police extended a "security hold" on the documents, according to a news release from the coroner's department. The release described the investigation as "thorough and comprehensive."
"The Los Angeles Police Department continues to investigate the events and related circumstances surrounding the death of Mr. Jackson," the release stated. "To maintain the integrity of its ongoing investigation, the Los Angeles Police Department has requested a continuance of the existing 'Security Hold' on all Department of Coroner documents related to the Jackson investigation. Further, the Los Angeles Police Department has requested that the autopsy findings regarding the cause and manner of death remain confidential."
Assistant Chief Coroner Ed Winter declined to comment on when the results may be released, according to The Associated Press. He said his office will not respond to queries on the completed investigation.
Jackson died June 25 at his rented home in Beverly Hills. Investigators have been trying to determine to what extent prescription drugs may have contributed to his death.
The autopsy report was widely expected to show that Jackson had been given propofol, a sedative known by the brand name Diprivan, which doctors say should not be administered except by an anesthesiologist in a hospital setting. Former Jackson associates have said the troubled pop star used the sedative to sleep.
News reports have quoted law enforcement sources as saying that Jackson was given propofol the night he died. A former Jackson nurse said the singer requested the drug to help him sleep.
Dr. Conrad Murray, a cardiologist who was serving as Jackson's personal physician, is an apparent focus of the police investigation. Investigators served warrants in recent weeks at Murray's office and a storage unit in Houston and at his home and office in Las Vegas.
Jackson apparently used more than two dozen aliases to obtain drugs with the help of doctors. Nineteen aliases have been cited in the affidavits used to secure search warrants against Murray.
The warrants also indicated that police were investigating whether the "offense of manslaughter" had been committed.
The development comes as a judge considers whether to name a special guardian to represent Jackson's children in various business agreements proposed for the singer's estate. Estate attorneys argued Monday that time is running short to make the deals happen.
Los Angeles Superior Court Judge Mitchell L. Beckloff adjourned the proceedings until later Tuesday afternoon to see if he can be persuaded that the children's interests can be sufficiently protected without the special guardian, whose role would be different from their natural guardian and paternal grandmother, Katherine Jackson.
Jackson's children areb Prince Michael Jr., 12, and Paris Michael Katherine, 11, whose mother is Debbie Rowe, and Prince Michael II, who was born through a surrogate mother whose name has never been revealed.