LAS VEGAS (AP) — Police believe a batch of drugs blamed in Michael Jackson's death was purchased by his personal physician at a Las Vegas pharmacy, court documents released Friday show.

Search warrant records released by a Nevada judge revealed that police found receipts in the Las Vegas medical office of Dr. Conrad Murray showing he bought the powerful sedative propofol from Applied Pharmacy Services on May 12.

Murray, 56, a cardiologist, is the focus of a homicide investigation by Los Angeles police into the June 25 death of the 50-year-old pop music icon. Murray has not been charged with a crime.

The newly unsealed affidavit showed that police tracing the manufacturing lot numbers of propofol bottles found at Jackson's bedside learned that Murray bought five, 100-milliliter bottles of the drug from the Las Vegas pharmacy as part of an order costing $853.

He paid $65 extra to have it sent to him by overnight express, the document states.

Clark County prosecutor David Schubert said the warrant didn't provide insight about how much of the drug Jackson was using or how long Murray's order was expected to last.

"Whether it was a week's worth or a month's worth, we have no way of knowing," Schubert said.

Los Angeles police fought to keep the records of the Aug. 11 search sealed. A detective argued that releasing the documents before Jan. 18 would jeopardize the investigation.

Attorneys representing The Associated Press, Los Angeles Times, TMZ Productions Inc. of Los Angeles and Stephens Media LLC, the parent company of the Las Vegas Review-Journal, argued there was no reason for the documents to remain secret.

Clark County District Court Judge Valerie Adair decided Thursday to unseal the records. Her order was signed Friday.

The Los Angeles County coroner ruled Jackson's death was caused primarily by propofol and another sedative.

In other documents, police said Murray told them he administered doses of propofol to Jackson in the hours before he died.

Murray told police he administered propofol to Jackson to help him sleep. He maintains that he didn't prescribe or administer anything to Jackson that should have killed him.