If you’re looking for a good read I suggest two books by Jack Kerley, The Hundredth Man and The Death Collectors. Jack Kerley debuted as an author with The Hundredth Man and then continued his epic tale with the sequel The Death Collectors, living up to his first novel.
The Hundredth Man is a “psychotic-killer-with-a-horrendous-childhood thriller” (Publishers Weekly) which follows the story of lead character Carson Ryder, a young detective who has a troubled past and is part of the newly formed two-man PSIT (Psychopathological and Sociopathological Investigative Team) unit, or referred to as Piss-it by fellow detectives, partnered with Harry Nautilus. The story follows the two through Piss-its very first case, finding a killer who leaves his victims headless, and also follows Ryder through his past and his confrontations with his brother who gives Ryder clues from an asylum which he resides.
The Death Collectors continues the epic tale of Carson Ryder and Harry Nautilus. This time the Piss-its team are investigating the bizarre murder of a naked female buried beneath flowers and surrounded by candles in a cheap motel. Even more dauntingly as the case progresses they end up chasing after a dead serial killer Marsden Hex Camp, who had been killed many years before in a courtroom, and on their investigation, they are involved in the collection and selling of murder memorabilia.