The Los Angeles County coroner has ruled Michael Jackson's death a homicide with a fatal combination of drugs given to the pop star hours before he died in late June, the Associated Press reported Monday.

Quoting a law enforcement official who spoke on condition of anonymity, the report said the powerful anesthetic propofol acted together with at least two sedatives to cause Jackson's death, adding that criminal charges will likely be filed against the doctor who was with him when he died.

The doctor, cardiologist Conrad Murray, is the target of a manslaughter investigation by the Los Angeles Police Department.

According to a search warrant affidavit unsealed Monday, Murray, who had been treating Jackson for insomnia, told investigators that on June 25 he injected 2 milligrams of lorazepam around 2 a.m., 2 milligrams of midazolam around 3 a.m., and repeats of each at 5 a.m. and 7 a.m., respectively, AP said.

They did not work and Murray told detectives that around 10:40 a.m. he gave in to Jackson's "repeated demands/requests" for propofol. He administered 25 milligrams of propofol and finally Jackson fell asleep, before Murray found he had stopped breathing, according to AP.

Dubbed the "King of Pop," Jackson died of then unknown causes on the afternoon of June 25 at age 50.