How Are Fingerprints Obtained From a Crime Scene?

A fingerprint is comprised of a collection of different swirling lines, each one completely unique based on the way the lines are formed and patterned. There are only seven different line types that make up different finger prints, but because the lines can start, split or stop at any point within the fingerprint, there are an endless number of patterns that can be created. The billions of different fingerprints that exist are comprised of many different angles, lengths, formations, widths and heights of these seven different line types.

Fingerprints left at crime scenes can be uncovered using several different methods. One of the most popular methods uses various adhering powders that are attracted to the oils present in fresh fingerprints. The fingerprint is made visible because the powder sticks to the oil imprint of the lines and ridges, forming the fingerprint. Another method for discovering fingerprints involves using either superglue, or Cyano-Acrylate, that vaporize when heated and the smoke attaches to the fingerprint in order to leave a visible white print. There are other methods that can be utilized in order to discover latent finger prints, but these typically involve specialized laboratory equipment that is not always available to crime scene technicians.

Fingerprint dusting methods work best with fresh fingerprints because they rely on our skin oils that are naturally secreted from the eccrine glands in our fingertips and are left behind on surfaces that we touch. Only the raised portions of our fingerprints actually touch the surface, which leaves a nice clear fingerprint behind. Fingerprinting dust clings to these skin oils, which is what allows the print to become visible.

Most fingerprints are initially run through state criminal fingerprint databases first. Not all state crime labs have access to the IAFIS database, even though the database is essentially free to use and is available for any crime lab to obtain. Typically, if a crime lab has no luck with a fingerprint search on a local level, they can turn to IAFIS in an attempt to find an out-of-state fingerprint match.

Originally fingerprints only had a great deal of purpose when it came to solving crimes that had already occurred, though fingerprinting is gaining popularity in other crime-fighting methods. Biometrics allow people to keep track of the public coming and going in some circumstances, such as entering a court house by first giving your fingerprint. Many states require you to give your fingerprint when you apply for your driver's license, or have a check cashed in order to prevent fraud. Children are being fingerprinted early so that if they ever go lost, it will be easier to find them because they are in the system. And some high profile buildings like banks have locks which rely on fingerprints in order to open them. So there is a lot more that a fingerprint can do than simply put a bad guy away. They can also keep people safe, and help keep track of people by storing them in the fingerprint database.

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