The Chemist - The Chemist Series, #1

The Chemist blends chameleon-like into everyday life. He is charming, intelligent, and a sociopath. His liquid sedative allows him to kidnap any victim he chooses, day or night, leaving no trace or clues behind. Lt. Cale Van Waring heads the Special Crimes Unit for the Green Bay PD. Three female victims have already vanished, with one headless body recovered from Lake Michigan. There are no suspects, no crime scene, and no witnesses.
Theories range from cults to witchcraft covens to serial killers. Yet, with no viable clues, the investigators grasp at any leads as they hunt for a killer who leaves no trace-one  intent on committing a string of "perfect crimes." Now a new victim has gone missing. City leaders are frustrated, the police brass angry, and Cale's fiancé issues him relationship ultimatums. Following a spotty trail, can Cale and his partners hunt down an invisible killer before he strikes again? Or does the Chemist have a more sinister plot in mind?