How to Analyze Fingerprints

Finding and Recording Fingerprints

Look for prints. In forensic fingerprinting, there are a few types of fingerprints and a few ways to find them. As you start looking for fingerprints, some will be visible (patent) and others will be invisible (latent). Search for patent ones first and place a marker of some kind by it remind you later. To search for latent prints, it can be good to use an alternate light source, such as a blue light with an orange filter. This helps make latent prints stand out. There are also ones called plastic prints which are in soft surfaces like soap.

Dust for latent prints. Once you have found the latent prints with an alternative light source, you need to dust them to make them more visible. Professionals use special powder, but for amateur home use, talcum powder or cornstarch is a great alternative. You'll also need a brush with a lot of soft bristles on it. With the light source still revealing the print, lightly dust the powder over it until it is sufficiently revealed. When using an alternate light source, it is most effective to turn the other lights in the room off, making the light more powerful.

Photograph the prints. For patent prints that are already visible and latent prints which you have revealed with light and dust, the best collection method is to take a picture with a high resolution camera. It is easier to study prints in photo form anyway. Make sure you take the picture close enough to see the details of the print. You always want to have a ruler of some kind next to the print to give a scale for how big it is. This is also helpful because it allows you to upload the prints onto the computer for analysis and file storage.

Determine the type of surface the prints are on. Fingerprints can be found on any surface. Surface types are categorized into porous, non-porous smooth, and non-porous rough. Things of a cloth nature, or anything water could seep into, are considered porous. Non-porous smooth would be things like glass or a varnished table. Non-porous rough would be a leather couch or a plastic container with a textured edge. This is important because the surface type can either make it easy or hard to lift a good print.

Lift the prints. Besides photography, the second way to collect the prints is to lift them with tape or gel. For smooth surfaces, lay a piece of clear tape over the print gently, then peel it off and place it on a white square of sturdy paper. You must be careful to lay the tape straight down on the print and not move it side to side at all as this might smudge it. For porous and non-porous rough surfaces, just the photograph is the easiest collection method, but there are other options. These require something that will get into the grooves, such as gel lifter or superglue. A gel lifter is a product specifically made for lifting prints from rough surfaces and it is laid over the fingerprint and creates a small 3D cast of the print. Superglue can be applied to the print and allowed to dry and then peeled off creating a mold. This gives you a backup to the pictures that you took and allows you to file a piece of physical evidence of the prints.

Match the prints. This is not easily done for someone without training or proper technology. If you have a set of known prints, you can compare the ones you lifted to those. Look for similar patterns to rule out some of the prints. There are advanced computer programs which can read dozens of points on a fingerprint and match those points to other known prints, but this is more for professional endeavors.

Reading Fingerprints

Choose which hand to read. You'll hear different schools of thought on which hand you should read, but there is one main thing which you can keep in mind. Almost everyone has a dominant hand, the one they write with and tend to perform most tricky tasks with. The dominant hand is the best to read in regards to the public self. It reveals things about you that the world sees. Reading the non-dominant hand will tell you things about the private self. Other methods say choose which hand based on male or female, or present life versus future life. In matters of your work life and career, the dominant hand is the one to read. Emotions, relationship issues, and your dreams are often revealed by the non-dominant hand.

Focus on the thumb. The way that fingerprints show up on each finger tends to reveal different things about a person, so a shape on the middle finger may not mean quite the same thing as a shape on the pinkie finger. As you get better at analyzing fingerprints, you can learn more about each finger, but for now start with the thumb. It is good to read the thumb because it is thought to be representative of the hand as a whole. The thumb is said to represent the person's overall identity.

Look at the basic shape. When you first start out, it can be good to press the thumb into black ink to reveal the ridges better and make it easier to read. There are three primary patterns of prints, which are the loop (most common), the whorl (second most common), and the arch (least common). There are even further distinctions, which are more rare, but these are what you will typically find. A loop looks kind of like a lasso. An arch looks like a wave or a bridge. A whorl looks like a bullseye. There are also variations such as the tented arch, which has a much steeper peak, and the composite whorl, which is sort of like a swirl or yin-yang sign.

Look for a loop. There are two types of loop, ulnar and radial, with ulnar meaning the loop opens toward the fingers and radial meaning the loop opens away from the fingers. Ulnar loops are the most common print and tend to be found on likeable people. This print can identify someone who is flexible and goes with the flow and is sociable and easy to get along with. The negatives of ulnar loop people tend to be that they are scattered and have a hard time organizing. They may also be restless, not quite feeling at ease. The less common radial loop represents someone who is open-minded and clever. They often live lives of altruism, giving to those in need. The downside for radial loop people is that if they do not stay centered, focused, then they will start to absorb too much stress.

Look for a whorl. This print shows up as a series of closed circles, or a spiral. This print tends to be found on people who may be a little self-centered, having a strong sense of independence and individuality. They are often rigid in their mindsets and can become overly focussed. The downsides of this print type are that they may have a short fuse and become angry easily. They also tend to lose interest in projects once they start them. Variations of the whorl include the peacock's eye, which resembles a peacock's feathers, and a composite whorl, which is sort of a series of circles that got smudged on one side.

Look for an arch. This print is often found on someone who is analytical and practical, always trying to figure out the best approach to situations. They are often not a fan of change and may be hard to get along with if they are particularly set in their ways. However, arch people often tend to be exceptionally loyal to the people they care about. This print comes in the variation of the tented arch, which is basically an arch with a much more pointed top. These people may be very open and friendly one day and closed off the next day.