The DEA’s investigation into Heath Ledger’s death is underway. The NY Daily News reports that a doctors in California and Texas are being investigated to see if they prescribed the painkillers Oxycontin and Vicodin to Ledger legally. Officials say that “it’s not clear if there was any wrongdoing.”

Heath died from a deadly combination of six prescription medications, the painkillers Oxycontin (oxycodone), and Vicodin (hydrocodone), anti-anxiety drugs Valium (diazepam), and Xanax (alprazolam), and sleeping pills Restoril (temazepam), and Unisom (doxylamine). From the statements of the medical examiner, he died from the combined effects of those drugs and not from taking too much of a single medication.

It’s possible that Heath obtained prescriptions over the Internet, considering that one of the doctors is in Texas and that the painkiller prescriptions are being investigated. We try not to speculate too much with this case, and there were a lot of inaccurate rumors immediately following his death. He traveled all over for his job and may have been legitimately prescribed drugs by different physicians without being warned of the possible side effects of mixing them.

Either way, his death shows that combining prescription medication can be deadly. A representative for the DEA told US Weekly “We’re trying to educate that legal drugs… can be just as dangerous as more hardcore drugs when misused or abused.”

According to TMZ, the prescription bottles found in Ledger’s apartment were nearly full, suggesting that he either rarely used them or was just starting new medications.

Update: Both doctors were questioned and cleared by the DEA, according to the NY Post. Neither doctor had prescribed the Vicodin or Oxycontin, but each had apparently given him prescriptions for other unnamed medications.