When did Captain Rumford die?

If you start the mission "Trailing the Coven" and leave New Tristram heading towards Old Tristram, you can find Rumford's corpse on a bridge not far from the town gates.

Clicking on him will make your character deliver a short eulogy (in my Witch Doctor's case, he said "Rest easy, friend..."). There's no in-game dialog that explains exactly how he died, but given the events of the mission prior, it's likely he was slain:

while trying to protect the town from the cultists who kill Deckard Cain and take Tyrael's sword fragments.

It doesn't show in the game until Act IV that he dies. I didn't know it until the ghost appeared. But it seems that Magdha and her followers killed him on their way to Tristram. Either that or some random Zombie got him while he was out strolling in the woods...