DI Murphy & DS Rossi - Book 1 - Dead Gone

A university student is murdered and attached to her body is a letter from her killer, detailing a famous unethical psychological experiment; an experiment that the killer had replicated on the victim, resulting in her death. Detectives Murphy and Rossi initially dismiss the letter as a bid to throw them off the scent-until more bodies are found, each with their own letter attached. The detectives realize they're chasing a killer who doesn't just want his victims' bodies, but their minds as well. As they rush to prevent any more deaths, they are forced to delve into the darkest channels of psychological research in an attempt to understand the motives of the madman.