"The first is that they were victims of an Abomination. When those creatures feed, they leave behind a trail of corpses not different from the one I showed you.
"The second one is that we are facing a vampire. They can feed off people's emotional energies, in which case they are better known as Incubus or Succubus, their blood, or their very life force.
"A victim of the third kind of vampire would resemble Lord Stern. I'm not really convinced by this hypothesis, though, since some of the deaths happened in broad daylight.
"The third and the worst one, is that we are against someone with the skills and the resources to employ Forbidden Magic right under our noses. It's a branch of magic that is universally outlawed because it requires living sacrifices to work.