Although fingerprinting has been around for thousands of years, we are now able to use fingerprints for more things then ever before. People use their fingerprints to get into locked rooms, onto their computers, and for time clocks at work (1). Fingerprints are also used for the reason that most of us know about, to identify victims, witnesses, and criminals in criminal justice cases. No two fingerprints have ever been found to be alike, and that is why it is the most commonly used forensic evidence in the world (2). Without it, many cases would never be solved.
There are three different types of fingerprints that can be collected, plastic, visible, and true latent (3). Plastic prints can be found in anything that leaves ridge impressions, like soap. Visible prints are ones that can be seen by the naked eye. This would be like if someone touched ink and then left a print on a wall. Finally, true latent prints are, “caused by the transfer of body perspiration or oils present on finger ridges to the surface of an object” (3). Regardless of the type of print, making sure that it is collected properly and without damaging it is crucial in any case.
While some of these fingerprints may be visible, many are not. It is important for investigators to carefully analyze the scene in order to not damage any potential prints. There are many different ways to discover and collect prints. The most common and well known is dusting with powder and using tape to collect them. By carefully spreading a powder over a surface, the particles attach to the ridges left by the fingerprint and it can carefully be lifted by tape. Different color powders are useful depending on the surface one is trying to get a print from (4). Surfaces that are absorbent may require a magnetic powder, while prints from blood require a chemical called Amido Black (4). Other lifting materials include rubber lifters, cellophane tape, and hinged lifters (4). The different methods of collecting prints depend on where the print is located. The video below demonstrates collecting latent prints with magnetic powder.
Once the print is collected, it is entered into a national database. In the United States, our database is called the Automated Fingerprint Identification System, or AFIS. The computer system used is the LifeScan Device. This computer scans in the fingerprint and it labels all of the minutiae, or individual characteristics, of that particular print. Whether you are getting your fingerprints taken for a job, or a print was found at a crime scene, it is entered into this database and saved with is unique markings labeled. If the print is entered into the computer in order to identify a person, the computer brings up the most likely matches and an examiner determines which one matches best (4). Having all of the prints that have ever been taken entered into one database makes the likelihood of identifying a person much more likely.
The most recent fingerprinting technique discovered was determined a few years ago in Britain. This technique allows for fingerprints to be detected, “on spent bullets and shell casings, even when the print had been wiped off. It works by detecting the minute corrosion of metal caused by sweat, which corrodes the metal in the shape of the fingerprint” (5). This is a groundbreaking discovery because it can determine the person that is responsible for using a weapon without that person having to touch anything else. The metal is dusted with a fine black powder that sticks onto corroded areas, allowing the print to be visible and lifted (5). The video below gives more information regarding this newly discovered technique.
Overall, fingerprinting is one of the most important pieces of evidence available in a case. Without it, many cases would never be closed and dangerous people would continue to roam the streets. Cases that were never resolved are now being looked at again due to the new technology revolving around fingerprints. I think being a fingerprint analyst would be such a unique and cool job, and fingerprinting will always be around. It’s crazy that every single person in the world has different fingerprints, and imagine where we would be without them.