And the mechanicals claim another. Shoulder shot.

Read this one. "STAY AWAY FROM THER SHOULDER BONE"

You neve know though. Lot's of times ther is no blood trail with out an exit hole. I would search for the deer if you havn'et already. He could be down close by.

That same thing happended to me but it was a hog. It ran 30 yards until it started bleeding a few drops of blood.

Sure sounds like a meat shot. Could have been the back or hind quarters too. Did your Dad see where the entrance was (where he hit the deer)? If you found 4 inches of arrow broken off, then you obviously have an exit wound too. I would try to pick up the blood trail in the direction the deer went. It could still be a fatal wound, maybe just not bleeding much right away.