The investigators are trying to reconstruct the medical history of the singer, who had a number of doctors over the years, the Los Angeles Times reported quoting sources familiar to the probe.

The Los Angeles Police Department (LAPD) officials have zeroed in on at least five physicians who prescribed medication to Jackson, according to the sources.

A Los Angeles County Superior Court spokesman confirmed that Judge Charlaine Olmedo signed off on three searches but said that information related to the probe could not be made public.

"Everything about them is sealed, but they do exist," said spokesman Allan Parachini.

The police had earlier recovered two bags of medical evidence from Jackson's rented home in Holmby Hills, where the pop star died after a suspected cardiac arrest on June 25.

The US Drug Enforcement Administration has already joined the coroner and the LAPD in the the probe.

Earlier, reports claimed that Propofol, a powerful sedative, was recovered from Jackson's home.

Several bottles of the medicine, sold under the brand name of Diprivan, were found at the pop star's home. Some of the bottles were full and others were empty, the source said adding that the investigators are trying to determine how Jackson got these drugs.

A powerful sedative, the medicine is used to put people under anesthesia before surgery and is available only to doctors.

Close Jackson's aides have also confirmed popstar's dependency over prescription drugs but at this point of time their role in the singer's death remains unclear.