Was Michael Jackson murdered?

I used that headline the day after the death was reported, and today I see "LAPD not ruling out homicide in death of Michael Jackson, top cop says":

Depending on "corroboration from the coroner's office as to the cause of death," [Police Chief Bill] Bratton suggested the investigation could lead to criminal charges. Detectives are focusing on five doctors who had treated Jackson in the past and whether they supplied him with the powerful sedative Diprivan.

Bratton is certainly not saying that the doctors may have intentionally killed Jackson.