Detective Kevin Marx is a detective from the homicide division of the Tulsa Police Department. He and Detective Martin interrogate Zoey Redbird twice in Betrayed: once after Chris Ford has been discovered dead and Brad Higeons was discovered missing, and once after both Chris and Brad were found dead and Heath Luck has gone missing.
- Marx is taller than Detective Martin
- Marx is very caring and understanding about the vampyre ways of life
- Marx is very caring towards Zoey, especially understanding of the death of her roommate, Stevie Rae Johnson
- Marx's twin sister Anne was Marked when they were teenagers and they still keep in touch