The investigation into Michael Jackson's death deepened late Wednesday with word that federal authorities will step in to help local police take a look at Jackson's doctors and his medications.

The Drug Enforcement Administration was asked to help the probe by the Los Angeles Police Department, a law enforcement official in Washington told The Associated Press on condition of anonymity because of the sensitivity of the investigation.

Following Jackson's death, allegations emerged that the 50-year-old King of Pop had been consuming painkillers, sedatives and antidepressants.

The federal agency can provide resources and experience in investigating drug abuse, illicit drug manufacturers known as "pill mills" and substances local police may not be familiar with, the official said.

Also Wednesday, a plan to bury Michael Jackson at his sprawling Neverland ranch collapsed, leaving details about his funeral undecided. Another mystery was solved: His newly unveiled will says his mother should raise his children, or failing her, Diana Ross.

The changing funeral circumstances thwarted many Jackson fans who had descended on the estate in the rolling hills near Santa Barbara with the hope of attending a public viewing.

"We're terribly disappointed," said Ida Barron, 44, who arrived with her husband Paul Barron, 56, intending to spend several days in a tent.

"We were going to listen to music and watch Michael Jackson DVDs and party all night long, not just to have fun, but in memory of Michael Jackson," Paul Barron said. "Now we're going to have to just go home."

Jackson's 7-year-old will, filed Wednesday in a Los Angeles court, gives his entire estate to a family trust and names his 79-year-old mother Katherine and his children as beneficiaries. The will also estimates the current value of his estate at more than $500 million.

Katherine Jackson was appointed their guardian, with entertainer Diana Ross, a longtime friend of Michael Jackson, named successor guardian if something happens to his mother. Ross introduced the Jackson 5 on the Ed Sullivan Show in the late 1960s and was instrumental in launching their career.

Meanwhile, Jackson family spokesman Ken Sunshine said a public memorial was in the works for Jackson but wouldn't be held at Neverland. In addition, it appeared more likely that a funeral and burial would take place in Los Angeles, a person familiar with the situation told the AP.

But the person, who is not authorized to speak for the family and requested anonymity, said nothing was planned for Neverland, at least through Friday.

The person said billionaire Thomas Barrack, who owns Neverland in a joint venture with Jackson, sought an exemption to bury the singer at the ranch. But the person says it's a complicated process and it couldn't be done for a burial this week.

"The family is aware a Neverland burial is not possible. They are expected to make decisions about whatever funeral and memorial service" will take place, the person said.

Heavy construction equipment and workers were seen passing through the wrought-iron gates of Neverland on Tuesday. It wasn't clear what they were doing. The property is about 120 miles northwest of Los Angeles.