nope, he doesn't defuse the graves if you kill him.
I note that a rat said the room was full of gold. I dug up all the graves (fire immunity) and... no gold.
if there's gold in here, or some secret room, I'll be damned if I can find it.
I DID however find a magic unlock scroll buried near the portal. walk from the portal towards the ruined stairs, and you should spot where to dig.
