alright...spoiler...but you asked for it.
you have ot fight bohdi later on.
right now, you need to go back up stairs to that main room and there is a room off to the right that has lots of spikes and pool of blood in the middle. that is where you fight him. then go to where the coffins are and drive a stake through the coffins and that is when bohdi will appear...be ready
I would be a serial killer if i didn't have such a strong distaste for manual labor