Fingerprint scanning. Computer artwork of a fingerprint scan with markings (red dots) showing the positions of characteristic features. A computer locates the features on the image that together make the fingerprint unique. Each feature's position is calculated with reference to the others, and this information is stored in a computer database as binary code (ones and zeros). Forensic scientists use fingerprints to identify people who were at a crime scene. Fingerprints may also be incorporated in passports or ID cards, or be used as a type of key, only allowing entry to recognised people.