Investigators may take fingerprints of victims, victim’s friends, family members, and suspects. When recording fingerprints of these people, workers roll the fingers in ink. Then they press it onto a paper card. Electronic copies of the cards can be saved to computer databases.
Some police stations can also use electronic fingerprint systems. They take pictures of the fingers, which are then stored in the database.
When fingerprints are found at a crime scene, investigators usually put tape on the fingerprints developed with metal powder. CSI’s also may take photos of the fingerprints, using strong light sources to see them easier.
There is also a method called latent detection, where investigators use special chemicals to see fingerprints not visible to the naked eye.