Killers Dot Com by Ian Hornby
Approx. 125,040 words.
Published on December 24, 2012 by
Two killers - one male, one female. Respectable in normal life, but when they leave that normality behind they fit the statistical patterns - sexual motivated with a firm belief they police are too stupid to catch them.
Their killings start as random, opportunist acts of brutality. Killing because they can. Dark, evil Kieran sets a mysterious pattern, taunting the cops to try and find it.