Blake Heron, the actor who played Marty Preston in the 1996 movie, "Shiloh," was found on his couch, unresponsive, and his girlfriend tearfully called 911 to try to save him.

TMZ broke the story, Blake was found dead Friday morning ... of an apparent drug overdose.

In the 911 call, you hear the girlfriend say Blake's jaw is clenched, which is a sign rigor mortis has set in.

The dispatcher holds out hope and tells the girlfriend to get Blake on the floor and tells her how to do CPR. You hear her in agony, crying, "He's dead. He's dead."

Blake was 35.