Authorities investigating Michael Jackson's death referred to him as an "addict" and were seeking evidence related to the powerful anesthetic propofol, according to search warrants released Thursday.

The documents show investigators have cause to believe several California Business and Professions codes had been broken, including "excessive prescribing," a misdemeanor punishable by a fine or imprisonment for up to 180 days.

Los Angeles police and federal Drug Enforcement Administration agents spent much of Tuesday at the Las Vegas home and business of Jackson's personal doctor, Conrad Murray, who is the focus of a manslaughter investigation. The raids sought evidence supporting that charge, as well as code violations, including "prescribing to an addict" and "unprofessional conduct."

The state codes cover all prescribing professionals, including doctors and dentists, and violations could lead to a revoked or suspended license, said Kimberly Kirchmeyer, deputy director of the Medical Board of California. The codes state a physician cannot prescribe drugs to anyone with a chemical dependency or who is using the drugs for non-therapeutic purposes; they define an addict as someone who continues to use a drug despite harm, shows compulsive use or has impaired control over use.

The warrants, which had been sealed when the searches were conducted, also said investigators wanted all documentation relating to the "purchase, transfer, receiving, ordering, delivery and storage of propofol."

A law enforcement official earlier told The Associated Press that on the day Jackson died Murray gave him propofol to help him sleep and that investigators are working under the theory the anesthetic caused Jackson's heart to stop. The official spoke on condition of anonymity because the investigation is ongoing.

A cause of death has yet to be announced. The Los Angeles County coroner has twice said toxicology findings on Jackson were imminent but after meeting Thursday with investigators Assistant Chief Coroner Ed Winter announced an indefinite delay. Winter said further investigation needs to be done; he did not go into detail.

Propofol, dubbed "milk of amnesia," is commonly used for surgeries and is not meant as a sleep agent or to be given in private homes. Because of its potency, only trained anesthesia professionals are supposed to administer it and patients are to be monitored at all times.

Murray, a cardiologist, has spoken to police but not commented publicly since Jackson died June 25. His attorney, Edward Chernoff, did not comment Thursday, but has previously said the doctor did not prescribe anything that "should have" killed Jackson.

Jackson was given anesthesia for numerous medical procedures over the years and had a long history of prescription drug use.

Search warrants issued last week in Houston allowed authorities to search Murray's clinic and a storage unit. They were the first public acknowledgment that investigators consider Jackson's death a possible manslaughter and that Murray is the target of the investigation.

The Las Vegas warrants were far more detailed and authorized authorities to look for medical and other records related to Jackson or any of the apparent 19 aliases he used, including the names Omar Arnold, Josephine Baker, Paul Farance, Jack London and Michael Amir Williams Muhammad.

Among the items seized in the Vegas searches were an iPhone, copies of several computer hard drives, a CD with the name Omar Arnold on it and a binder containing invoices for medical equipment and supplies. No propofol was found.

The warrant also shows investigators are seeking correspondence from seven doctors it names. One, Dr. Allan Metzger of Los Angeles, is an internist and rheumatologist who had a close relationship with Jackson beginning in 2002 and was godfather to one of the singer's children, said his attorney, Harland Braun.

Braun said Jackson invited Metzger to his home April 18. He spent about an hour and a half with him, during which time Jackson asked about sleep medication, particularly propofol.

Metzger told him it was dangerous, could be life threatening and should not be used outside a hospital, and suggested Jackson use some other sleep medication, Braun said.

Metzger's experience echoed Cherilyn Lee, a registered nurse who gave Jackson nutritional counseling earlier this year, who said he complained of insomnia and asked her repeatedly for Diprivan, the brand-name version of propofol. Lee said she also warned him of the drug's dangers and rejected his requests.

(China Daily/Agencies July 31, 2009)