Fisherman's Catch

A first ever sighting and case of the infamous Offenderman in LA. But according to the FBI, LA's Homicide has the whole story wrong. After the FBI has been after him for years, Homicide accidentally gets a case of Offenderman. Both squads have to work together unfortunately to bring Offender to "justice" or whatever the government has placed as punishment for Offender. But, only if they find him soon. Unfortunately the public is not so reliable as this case has to be top secret and hidden from civilians at all costs. Will they catch him? Or waste years of effort for the cases to be labelled as cold?
(Crossover fanfiction of TV series The Killing and internet horror stories known as Creepypastas.)