Well... [ Not exactly prepared for this question, but alright...] If we're talking about the mythological creature, that's... a bit outside my area of expertize, to be honest. There is a variety of paraphilia called clinical vampirism or Renfield's syndrome that manifests in an obsession with drinking blood. People that suffer from this condition are primarily male and the craving for blood arises from the idea that it conveys life-enhancing powers, so not unlike the vampires of myth.
Serial killers Peter Kürten and Richard Trenton Chase were both called vampires by the tabloids after it was discovered that they drank the blood of their victims, and there was an unsolved murder in Stockholm, Sweden in 1932 that was nicknamed "the Vampire killer" due to the circumstances of the victim's death. Very few cases of the syndrome have been described though and there's still some uncertainty surrounding the actual condition.
[ And now that he's done going slightly off-track.]
That said... I do believe that since we're all brought here as "criminals", it's important to think of our time here as a clean slate. With the, uh... the blood shack serving as a safe way for vampires to feed, killing becomes less of an act of survival and as such any murder for whatever reason will be treated as such. Of course, I can't speak for the entire Defense Force, but that's my personal belief.