Detectives investigating the death of Michael Jackson are looking at his prescription drug history and trying to talk with his numerous former doctors, the Los Angeles police chief said.

Meanwhile, Jackson's father, Joe, said in an interview with ABC News that he believed foul play was involved in his son's death.

But in the interview, shown on Good Morning America, he did not elaborate.

Los Angeles Police Chief William Bratton has said that police are waiting for the coroner's report before ruling out any possibilities in their "comprehensive" investigation into the sudden death of the 50-year-old pop star two weeks ago.

The coroner's report will determine the cause of death and hinges on time-consuming toxicology tests.

Bratton said detectives are gathering evidence, including items seized from Jackson's rented home and arranging interviews with his many doctors, but the police chief deferred to the coroner to determine the cause of death.

Jackson, who died on June 25, had a well-known history of using prescription medications, especially painkillers.

Joe Jackson said he didn't know anything about drugs his son was involved in. "I don't even know the name of them," he said. "I do know that whatever he was taking was to make him rest because he had been working so hard."

He told ABC News that he and his wife, Katherine, should have custody of Michael's three children. "They'll grow up to be strong Jacksons," he said.

He said Michael's daughter, Paris, who spoke at the memorial service, was taking the death hard and cried whenever Michael's name was mentioned. He said that she might have a future in the entertainment business along with the youngest son, nicknamed Blanket, who "can really dance".