Acting on a search warrant, a caravan of 15 cars descended on the clinic at about 10:20 a.m. Wednesday, with officers in Drug Enforcement Administration windbreakers seen entering the building.
Agents are focusing the investigation on the drug Propofol, the powerful anesthesia that Jackson may have taken before his death, a law enforcement source tells PEOPLE.
"It is Conrad Murray they're looking at," the source says. "They are looking for Propofol, along with anything else they find. But Propofol is the big one."
Attorney Denounces RaidDuring the raid, Murray was in Nevada, where he has another office. The doctor has already been interviewed twice by police and has denied wrongdoing.
"This [raid] was unexpected to us," Miranda Sevcik, a rep for Murray's attorney Ed Chernoff, tells PEOPLE. "All this drama is just not necessary, is how we feel. Ed's not dismayed about it. He's just trying to figure out what's going on. But he's not worried about it."
According Chernoff, Los Angeles detectives are seeking a third interview and have asked for medical records in addition to those Murray has already provided.
Doctor Feels Fury Toward Him"The coroner wants to clear up the cause of death, we share that goal," says Chernoff in a statement posted on his firm's Web site. "We don't have access to the most important information in this case ... the toxicology report. We're still in the dark like everybody else."
Chernoff adds: "Based on Dr. Murray's minute-by-minute and item-by-item description of Michael Jackson's last days, he should not be a target of criminal charges. Dr. Murray was the last doctor standing when Michael Jackson died and it seems all the fury is directed toward him."
Murray, according to his attorney, is "frustrated by negative and often erroneous media reports, he has to walk around 24-7 with a bodyguard. He can't operate his practice. He can't go to work because he is harassed no matter where he goes."
Murray plans to continue cooperating with authorities. The third interview date has not yet been set, his attorney says.
Additional reporting by ANNE LANGE