Last I played you could easily find out who the vampire dwarves were using one of a few methods.
One, engraving a slab or otherwise in memory of the dead dwarf will show who the vampire is under the dwarf's cause of death.
Two, vampires have absurdly long relationship lists.
Three, just keeping your dwarves in a communal sleeping area helps them spot potential vampires, but again you might run into the whole problem with them lying and framing others.
Four, if you keep a close eye on your dwarves' sleeping quarters, you'll notice a vampire when it goes to feed because it changes its symbol into the nightcreature symbol (
ñ). If you've caught him in a private room, you can simply forbid all the doors and leave him there to rot. Or fill the room with magma, if your doors can handle it or you've taken other precautions.
My personal favourite way of killing vampires as the overseer of my dwarves is setting up a gigantic pile of dirt or rocks supported by a single support, placing a lever beneath it, and assigning the vampire dwarf to pull that lever. Collapsing floors into spike pits works too.
Last edited by 4zb41; Dec 3, 2012 at 03:53 AM.