U.S. Federal Bureau of Investigation Tuesday released more than 300 pages of files related to the late pop king Michael Jackson who died on June 25 at the age of 50.

Pop star Michael Jackson waves to supporters as he leaves the Santa Barbara County Courthouse after he was found not guilty in Santa Maria, California in this June 13, 2005 file photo. Jackson died from a lethal dose of the powerful anesthetic propofol given in a cocktail of drugs, leading authorities to suspect his doctor of manslaughter, court documents showed on August 24, 2009. [Xinhua/Reuters File Photo]

The files were made public in response to a Freedom of Information Act request made by several organizations.

Most of the files are about a 1992 investigation of a man who threatened to kill the pop star and then-U.S. President George H. W. Bush.

The records include numerous threatening letters sent by the suspect whose name was concealed. The suspect eventually pleaded guilty to a federal charge of mailing a threatening communication and was sentenced to two years in prison, said the records.

The files also reveal the FBI's role in assisting California police in investigating child sexual abuse allegations against Jackson.

The first sexual abuse case in 1993 was closed without authorities bringing charges against Jackson, who finally settled a civil action for more than 20 million U.S. dollars.

The files also describe another child molestation investigation by the bureau in late 2004 that was closed when a witness, the files said, "advised the agents that he had no interest in testifying against" Jackson and "would legally fight any attempt to do so."