Federal drug investigators are probing two doctors over the death of actor Heath Ledger, the Daily News has learned.

The doctors - one in California, one in Texas - are believed to have supplied the “Brokeback Mountain” star with the powerful painkillers Oxycontin and Vicodin, law enforcement sources said. Authorities want to know if the drugs were prescribed illegally. “It’s an ongoing investigation,” a law enforcement source told The News Tuesday. “It’s not clear if there was any wrongdoing.”

The revelation came ...