Great point!
Have you checked out the movie Odd Thomas (free here)?:
Not winning any oscars, but in terms of content, total Grand Slam
It talks about evil spirits that will follow murders around, and feed off the energy of the carnage when they kill.
Reminded me of what this guy was saying about animal sacrifices in Roman times, and how the Gods were not interested in the material offering, they fed off the Prana energy in the blood that spilled on the alter: