At a crime scene, you never get to see the person that left the fingerprints. You don't know what they were up to, where they were or even what they touched, so you need 'dust' for them. When you dust for fingerprints, you diligently and meticulously search every surface looking for clues that will lead you to a deeper understanding of the situation and insight into the person who left the fingerprints.
Although we can't see God, He does leave fingerprints in our lives. Unlike a criminal, God wants to be found. A watchful discerning eye often reveals 'coincidences' that yield to an increased faith. Often we're so busy and distracted that we overlook the fingerprints completely and remain unaware of His presence and activity in our lives. By allowing ourselves to be distracted, we miss the fingerprints, and cheat ourselves out of the full and abundant life He offers us interacting with Him on a daily basis.