Authorities investigating the circumstances of Michael Jackson's death are relying in part on several bags of evidence they have removed over the last week from the pop star's Holmby Hills mansion, including prescription drugs that one source said were not in Jackson's name.
It will be several weeks before the Los Angeles County coroner's office determines whether prescription medications played any part in the singer's death.
But experts said prescriptions in multiple names would raise concern.
Abuse of prescription drugs has long been a problem for celebrities who often gain improper access to medications through willing doctors.
After producer Don Simpson died of heart failure caused by a massive overdose of cocaine and prescription medications in 1996, police discovered more than 2,200 pills stored in alphabetical order in a bedroom closet.
Many of the prescriptions were illegally written for him under a pseudonym.
Earlier this year, the California attorney general and the Los Angeles County district attorney's office filed charges against two of the doctors who cared for Anna Nicole Smith, who died of a drug overdose in 2007, in part because they had allegedly written prescriptions for her under pseudonyms.
Attorney Mark Geragos, who has represented both celebrities and their doctors, called the practice of writing prescriptions for celebrities under pseudonyms "dancing in the shadows."
"It's custom and practice that pseudonyms are used in fulfilling a lot of pain medications -- which doesn't mean it's legal, but it's done," Geragos said.
Prescription medicines were not the only items taken by investigators from Jackson's home; medical equipment was among the evidence removed Monday, law enforcement sources, who are not authorized to discuss the investigation, told The Times.
Investigators are trying to determine whether the medications found at the Holmby Hills mansion under names other than Jackson's were for people living at the house or whether pseudonyms were meant to conceal drugs intended for the pop star's use.
Like many celebrities, Jackson sometimes used other names to avoid attracting attention and constant intrusion by the tabloids -- especially in medical matters, a source said.
Adam Braun, a lawyer for psychiatrist Kristine Eroshevich, who treated Anna Nicole Smith in the final six months of her life, said earlier this year that the doctor used pseudonyms on prescription forms to avoid invasion of the model's privacy by a throng of tabloid reporters and photographers that followed her closely.
But several people interviewed by The Times said that often, people who employ pseudonyms to obtain prescription drugs -- usually painkillers -- are trying to hide their addiction from people around them.
Candis Cohen, a spokeswoman for the Medical Board of California, said that a physician could be disciplined for prescribing drugs to a patient under a pseudonym or alias.
When actress Winona Ryder was sentenced in 2002 for shoplifting, her probation report stated that the actress had had 37 prescriptions filled by 30 doctors from January 1996 to December 1998.
State board investigators found that a Santa Monica physician had written several prescriptions for the actress under her name as well as an alias. The doctor's medical license was later revoked.
When criminal charges were filed against Eroshevich, another physician who treated the model, and Smith's boyfriend and attorney, Howard K. Stern, the state attorney general and L.A. County district attorney said that the three had been charged with conspiring to prescribe, administer and dispense controlled substances to an addict.
More questions about Jackson's medications arose Tuesday when a registered nurse came forward to say Jackson had asked her in April for a powerful sedative.
Cherilyn Lee, who operates an L.A.-based nutritional counseling business, told The Times that Jackson, complaining of insomnia, pleaded with her for Diprivan, a drug usually used to start or maintain anesthesia during surgery.
Lee said she told Jackson, "This medication is not safe."
Four days before Jackson's death, Lee said one of the pop star's employees called her and said the singer was complaining that one side of his body was hot and the other side was cold.
Lee did not say that Jackson had ever taken Diprivan (propofol).
She said she told the employee that Jackson should immediately go to the hospital.
An injection of a dose of Diprivan can induce hypnosis within 40 seconds, according to the U.S. Food and Drug Administration.
The drug's product label said propofol should only be administered by persons "trained in the administration of general anesthesia."
Sedated patients should be continuously monitored, the product label says, and artificial ventilation, administration of oxygen and CPR "must be immediately available."
Jackson has struggled with medication issues since 1984, when he was burned while filming a Pepsi commercial.
In 1993, a world tour was canceled after the singer said he needed treatment for an addiction to a painkiller.
In a video statement released later, Jackson talked about his addiction to the drugs.
"I was humiliated, embarrassed, hurt and suffering great pain in my heart," he said. "I became increasingly more dependent to the painkillers to get me through the days of the tour. My friends and doctors advised me to seek professional guidance immediately in order to eliminate what has become an addiction."
Times staff writers Rong-Gong Lin II and Kimi Yoshino contributed to this report.