U.S. drug enforcement agents and Los Angeles police on Wednesday raided a Houston clinic owned by Conrad Murray, the doctor who was with pop icon Michael Jackson when he died, searching for information on the singer's use of the anesthetic, propofol.

Agents with the U.S. Drug Enforcement Administration entered the Armstrong Medical Clinic in north Houston to serve a search warrant in an effort to help Los Angeles police probing the death of the Thriller singer, said Rusty Payne, a Washington-based spokesperson for the agency.

Payne declined to give details because the Texas search warrant remained sealed.

A Los Angeles police spokeswoman confirmed that their detectives served the warrant with the assistance of the DEA, but declined to say what investigators were looking for.

One law enforcement official, who declined to be named, said the focus of the search was the strong narcotic propofol, also known as Diprivan, which has repeatedly been named in media reports as a drug Jackson was said to be taking before he died on June 25.

Murray's attorney, Ed Chernoff, was not immediately available to comment, but said in a statement posted on his website on Tuesday that his client was continuing to cooperate with investigators looking into the cause of Jackson's death.

JACKSON'S DRUG USE

Jackson, 50, died of cardiac arrest at his rented Los Angeles mansion just a few weeks before a planned string of 50 comeback concerts in London.

Since then investigators from several California agencies and federal DEA officials have focused their probe into the cause of death on the Thriller singer's prescription drug use and doctors who may have provided the drugs to Jackson.

Los Angeles officials have repeatedly declined to confirm those reports, and an official cause of death is pending results of toxicology tests.

A spokesman for the Los Angeles coroner's office, which is one of the agencies looking into Jackson's death, said a report should be released at the end of next week, but he declined to comment on whether a cause of death had been determined.

He said the coroner's office was not involved in the Houston raid.

Murray, who was hired to be Jackson's personal physician ahead of the London concerts, has told police he did not inject the singer with painkillers before his cardiac arrest.

After questioning Murray back in June, Chernoff's law firm issued a statement saying at the time, that Investigators say the doctor is in no way a suspect and remains a witness to this tragedy.

Los Angeles California