Detective Mahoney (first name unknown) is a recurring character in Tim Dorsey's series of novels. He first appeared in Orange Crush, although he later appeared in Triggerfish Twist (which was set in 1997, before the events of Crush). Mahoney often speaks in the bizarre, now anachronistic lingo of film noir-style detective movies from the 1940s.
Mahoney is deeply interested in serial killers in general, and has focused on Serge Storms in particular to the point of near-obsession. A map on Mahoney's office wall is covered in push pins representing sightings both of known killers and his ex-wives. Storms and Mahoney have crossed paths at least three times, and they appear to maintain a certain respect for each other.
A running joke is that Mahoney calls every bartender he meets "Louie", and takes "your money's no good here" as a compliment. In fact, the first bartender he meets in Orange Crush really is named Louie, and uses "your money's no good here" as a compliment; on other occasions, the references have been less appropriate.
By 2004, the setting of Cadillac Beach, Mahoney's mind has broken. Trying to understand Serge has driven him insane, and a pair of FBI detectives tracking Serge find Mahoney in a mental institution, speaking entirely in complex detective slang.
By 2007, the setting of Hurricane Punch, Mahoney was free from the institution, but seeing a therapist, because his mind had trouble distinguishing fact from pulp fiction.
The end of Electric Barracuda reveals Mahoney is actually Serge's older brother, who was put up for adoption before Serge's birth.