Help me ID a movie, maybe it's this one?

A detective trying to solve murders has no witnesses who can ID the face of the suspect so he constructs a "mannequin" using other elements of the descriptions given - height, weight, shape, type/color of suit, etc. He then holds a "line-up" for all the witnesses/victims with a dummy standing in for the man. He has the composite picture (minus the face, of course) given out to patrolmen.

At one point in the film the detective is shown in his darkened office with the dummy sitting on a chair. The detective looks out the window and says something like "I'll find you" then walks out. The dummy then stands! It was the actual killer sitting there all along. Very cool scene.

Thanks for the help.