#3,745,455,191 Demonic Martyr or DD does ~9000 damage?

I had just downed lady stormflay in a Vaal City map, picked up items and went to town, and vendored for three or four minutes. I then returned to the map to get more rares, walk over, grab something and then get one hit. I assume it was detonate dead or a Martyr as I didn't see anything attacking me.

Are you able to tell what killed me? Not knowing how I died has taken all my motivation away from playing this game.

same thing here mate :) , now we are free ;)