Vengeance in Death (In Death, #6)

In a time when technology links the law and the lawless, predators and prey can be one and the same. He is an expert with the latest technology...a madman with the mind of a genius and the heart of a killer. He quietly stalks his prey. Then he haunts the police with cryptic riddles about the crimes he is about to commit - always solved moments too late to save his victims' lives. Police lieutenant Eve Dallas finds the first victim butchered in his own home. The second loses his life in a vacant luxury apartment. The two men had little in common. Both suffered unspeakable torture before their deaths. And both had ties to an ugly secret of ten years past - a secret shared by none other than Eve's new husband, Roarke.