NEW YORK -- A cocktail of prescription drugs was found in Michael Jackson's blood when he died, including one normally used by psychiatriac patients, Montreal author Ian Halperin told Sun Media yesterday.

Halperin says he has seen a portion of the autopsy results.

"The toxicology tests revealed that Michael Jackson didn't only have propofol or demerol in his blood, but many drugs, including one normally used for psychiatric purposes," said Halperin, whose newly published Unmasked: The Final Years of Michael Jackson tops the New York Times bestseller list for non-fiction hardcover books.

Halperin said he was provided the autopsy information from a source inside the Los Angeles Police Department, with whom he has collaborated for 15 years on previous celebrity books.

The investigation is proceeding carefully, Halperin's source said, and the autopsy results probably won't be released soon.

"They don't want to accuse anybody unless they are sure their investigation is air tight," Halperin said. "They can't be wrong. The whole world is watching. They have over 20 doctors to interrogate, who are sweating right now."

Dr. Conrad Murray is first on the investigators' list, Halperin confirmed.

Murray's Las Vegas office and sprawling home were searched by authorities yesterday, seeking documents as part of their manslaughter investigation. Murray, 51, was Jackson's doctor only since May. He was supposed to accompany the singer during the 50-date concert series in London this summer.

Los Angeles police and federal Drug Enforcement Administration agents entered Murray's home in a gated community, while others across town searched Murray's medical offices. Murray was at the home during the search.

Warrants were sealed and officials couldn't say what documents agents were seeking.

Last week in Houston authorities searched Murray's clinic and storage. Court records show they were seeking evidence of whether the doctor committed manslaughter.

Police have said Murray is cooperating.

Murray told investigators he administered propofol -- a powerful anesthetic to help the singer sleep -- to Jackson on the day he died, as he'd done many times previously, a law-enforcement source told The Associated Press.

Jackson relied on propofol like an alarm clock, AP's source said, explaining that a doctor would administer it when Jackson went to sleep, then stop the IV drip when the singer wanted to wake up.

Using propofol to sleep exceeds the drug's intended purpose. The drug can depress breathing and lower heart rates and blood pressure. Home use of propofol is virtually unheard of. Because of its risks, propofol is supposed to be administered only in medical settings by trained personnel, with uninterrupted monitoring.

Meantime, in Los Angeles yesterday the legal team for Jackson's mother asked a judge for the power to press the special administrators of her son's estate for more information. Lawyers for Katherine Jackson requested the authority to move ahead and subpoena attorney John Branca and former music executive John McClain. They want to interview the men, who were named in Jackson's will as executors, and dig through their records.

A Superior Court judge will deal with their request Monday, along with other matters.

-- with files from The Associated Press