Costume

Detective-  smart/ casual outfit, professional look. Long coat, shirt, smart trousers, leather shoes.
This outfit will clearly show to the audience that this character is the detective because of the smart, professional look, typical of a detective.
Suspects- Hoodies, casual look. Faces will be hidden throughout the scene to keep their identity hidden.
The hoodies worn by the suspects will contrast with the smart costume of the detective. The audience will be able to tell that they are the suspects and would feel suspicious about them because of their hoodies as these are often seen as a means of concealing ones identity.