What aspects of the crime scene as observed by al Dewey examining photographs foreshadow the eventual capture of the suspects?

Al Dewey observes the bloodstains, footprints, and other evidence at the crime scene, which provide clues for tracking down the suspects. The bloodstains can be analyzed for DNA evidence, footprints can be matched with suspects' shoes, and other trace evidence can link the suspects to the scene, ultimately aiding in their capture.