LOS ANGELES (AP) - Questions about Michael Jackson's use of prescription drugs are intensifying after a powerful sedative was found inside his home.

The drug Diprivan, an anesthetic widely used in operating rooms to induce unconsciousness, was found in Jackson's residence, a law enforcement official said Friday. Also known as Propofol, it's given intravenously and is very unusual to have in a private home.

The official spoke on condition of anonymity because the person was not authorized to comment about the matter.

A Los Angeles Police spokesman, Lt. John Romero, declined to discuss the case. "It's an ongoing investigation," he said.

The cause of Jackson's death has not been determined. Autopsy results are not expected for several weeks.

The city was planning for a massive crowd at the singer's memorial service. At the downtown Staples Center, where Jackson's memorial will be held Tuesday morning, Assistant Police Chief Earl Paysinger said anywhere from 250,000 to 700,000 people could try to reach the arena, even though only 17,500 tickets will be available.

City Councilwoman Jan Perry urged people to stay home and watch the memorial on TV. There will not be a funeral procession through the city.

Tickets to Jackson's memorial service will be free. They can be obtained by registering at Staplescenter.com. There will be 11,000 tickets for seats inside Staples Center and 6,500 for seats in the adjacent Nokia Theatre, where fans can watch a simulcast. On Saturday night, 8,750 names will be randomly selected to receive two tickets each.

No details about the memorial service itself were released.

Jackson was known to have suffered from severe insomnia. In the weeks before his death, Cherilyn Lee, a registered nurse who was working with the singer, said Jackson pleaded for Diprivan amid the stress of preparing for a massive series of comeback concerts.

Lee said she repeatedly rejected his demands because the drug was unsafe.

Told Friday that Diprivan had been found at Jackson's house, she said, "I did everything I could to warn him against it."

Jackson had trouble sleeping as far back as 1989, said one of his former publicists, Rob Goldstone, who spent a month on the road with Jackson during the "Bad" tour.

"He had very bad nightmares, he found it very difficult to sleep," Goldstone said.

Diprivan, which has a milky appearance, is sometimes nicknamed "milk of amnesia." Last fall, doctors from the Mayo Clinic warned at a conference that in rare cases, Diprivan can trigger an irreversible chain of events leading to heart dysfunction and death.

They said three patients receiving Diprivan to treat severe seizures had suffered cardiac arrest, and two died. The doctors said the clinic stopped using Diprivan to treat such patients because of the danger.

The drug's manufacturer, AstraZeneca PLC, warns that patients using Diprivan should be continuously monitored, and in a tiny number of cases patients using it have suffered cardiac arrest, although it was not clear the drug was to blame.

Authorities are investigating allegations that the 50-year-old Jackson had been consuming painkillers, sedatives and antidepressants. Any criminal charges would depend on whether Jackson had been overly prescribed medications, given drugs inappropriate for his needs, or if doctors knowingly prescribed Jackson medications under an assumed name.

Edward Chernoff, an attorney for Jackson's doctor, Dr. Conrad Murray, said Friday through a spokeswoman that he had agreed with investigators not to comment until information is released through official channels. Murray was in Jackson's rented mansion when the singer went into cardiac arrest in his bedroom on June 25.

Murray has spoken to police and authorities say he is not a suspect. In an earlier interview, Chernoff said Murray never gave or prescribed Jackson the painkillers Demerol or OxyContin, and denied reports suggesting that the doctor gave the pop star drugs that contributed to his death.

Chernoff would not discuss what drugs the doctor administered to Jackson, but said they would have been prescribed in response to a specific complaint.

AP Entertainment Writer Lynn Elber and AP Music Writer Nekesa Moody contributed to this report.