https://www.wired.com/story/technique-tutorial-crime-scene-fingerprints/

In the fictions of Mark Twain and CSI and more, the identification of fingerprints is one of the most well-known methods for solving crimes. In real life, collecting fingerprints left on a window or doorknob is a delicate science, as well as an important one. Preserving fingerprints can help definitively link a person to a crime, especially since the US government maintains biometric databases of prints from millions of people—including previously convicted and suspected criminals, government employees, military personnel, and others.

To learn more about the science of fingerprint collection, WIRED caught up with Matthew Steiner, a certified senior crime-scene analyst with more than 20 years of experience. He demonstrated how to lift fingerprints off different surfaces, so they can be viewed under a microscope.