Detective stories are stereotypically full of over-the-top metaphors: "The villain's hand stroked the cat the way his sins stroked his black soul. His voice, rough as the city's nighttime streets and twice as terrifying, barked orders to his lackeys. They scattered like parents who just realized they forgot to pick up a child from school." Write a short scene using some of your own extreme metaphors and similes.
The closest I've ever come to writing detective fiction was years ago, when leemoyer and I passed the time on a roadtrip by developing a mini-outline for a short story to be called Murder On The Two-Man Luge. The luge speeds down the track, and upon arriving at the bottom, it is discovered that the man in back has been killed.
It has no good metaphor to tie it to this challenge, but it does have this moment of homage: the investigating officer looks over the scene and exclaims, "Round up the usual suspects."