No Conrad Murray in Prince's Death

Prince's deadly dose of the powerful painkiller Fentanyl was NOT prescribed by a doctor, which means it's a near impossibility anyone will ever be charged with his murder.

Law enforcement sources confirm investigators have not turned up a prescription for the Fentanyl. The Fentanyl pills found at Paisley Park were in a bottle labeled hydrocodone -- and it's now believed they were illegally obtained.

Our sources tell us whoever gave Prince the drug would face a 3rd degree murder charge under Minnesota law. However, without a prescription, we're told Prince's doctors would be in the clear ... so there'll be no Conrad Murray-esque trial.

Investigators would have to track down the source of the illicit Fentanyl -- it's reportedly an epidemic problem in Minnesota -- for anyone to stand trial for murder.

It's still possible a doctor could get nailed for over-prescribing other opioids. Remember, we broke the story ... Prince nearly OD'd on Percocet 6 days before his death at Paisley Park.