Fingerprints and the Science of Fingerprinting
Fingerprints and the Science of Fingerprinting
Fingerprints are the prints which we have on our fingers i.e., it is an impression of the friction ridges of all or any part of the fingers. The ridges assist in gripping rough surfaces, as well as smooth wet surfaces.
Fingerprints are the tiny ridges, whorls and valley patterns on the tip of each finger. They form from pressure on a baby's tiny, developing fingers in the womb. No two people have been found to have the same fingerprints -- they are totally unique. There's a one in 64 billion chance that your fingerprint will match up exactly with someone else's.
Fingerprints are even more unique than DNA, the genetic material in each of our cells. Although identical twinscan share the same DNA -- or at least most of it -- they can't have the same fingerprints.
Fingerprints are one of many forms of biometrics used to identify an individual and verify their identity. It is the one of the best forms of physical evidence left at a crime scene. Fingerprints offer an infallible means of personal identification . The science of fingerprint Identification stands out among all other forensic sciences. No two fingerprints have ever been found alike in many billions of human and automated computer comparisons. Even the fingerprints of two identical twins are different. Fingerprints are the very basis for criminal history foundation at every police agency on earth. It has helped and are helping in the idendification of criminals. Because of the ability of the fingerprinting field it is now virtually impossible for a crime to go unsolved where the fingerprint of the suspect is present. Because of the great technological advancements in the area of fingerprint technology, crimes have been solved and will continue to be solved in the future. In perhaps one of the most noted cases in American history, it was a palm print found on the stock of a rifle that was used in the conviction of Lee Harvey Oswald for the assassination of President John F. Kennedy . As seen in the case of President Kennedy, fingerprints are one of the most valuable pieces of evidence found at the scene of a crime. Although a fingerprint is sometimes very small in size, its value to the police is immense.
Today, fingerprints are also used to prevent forged signatures, identify accident victims, verify job applicants and provide personalized access to everything from ATMsto computer networks.
1686 - Malpighi
In 1686, Marcello Malpighi, a professor of anatomy at the University of Bologna, noted in his treatise; ridges, spirals and loops in fingerprints. He made no mention of their value as a tool for individual identification. A layer of skin was named after him; "Malpighi" layer, which is approximately 1.8mm thick.
1823 - Purkinje
In 1823, John Evangelist Purkinje, an anatomy professor at the University of Breslau, published his thesis discussing 9 fingerprint patterns, but he too made no mention of the value of fingerprints for personal identification.
1888 - Galton
Sir Francis Galton, a British anthropologist and a cousin of Charles Darwin, began his observations of fingerprints as a means of identification in the 1880's.
The three basic patterns of fingerprint ridges are the arch, loop, and whorl. An arch is a pattern where the ridges enter from one side of the finger, rise in the center forming an arc, and then exit the other side of the finger. The loop is a pattern where the ridges enter from one side of a finger, form a curve, and tend to exit from the same side they enter. In the whorl pattern, ridges form circularly around a central point on the finger. Scientists have found that family members often share the same general fingerprint patterns, leading to the belief that these patterns are inherited.
The other patterns of fingerprints are accidental, double loop, central pocket loop, plain whorl, and tented arch.
- Loops – Loops make up almost 70 percent of the patterns that have been encountered so far. A loop pattern is basically the existence and combination of one delta and one core and a ridge count. There are basically two types of loops – ‘ulnar’ and ‘radial’.
- Whorls – Whorls constitute around 25-35 percent of the patterns that have been brought in and mainly consists of whorls. A fingerprint pattern that contains 2 or even more deltas will always be a whorl pattern.
- Plain Whorl – A plain whorl is that whorl that consists of at least one ridge that could possibly make a complete circuit, with 2 deltas, where an imaginary line will be drawn and it should have at least 1 recurving ridge.
- Central Pocket Whorl – This type of a whorl consists of one recurving ridge, 2 deltas, an obstruction to the line of flow and no recurving ridge inside the pattern area is touched or cut.
- Double Loop Whorl – This whorl is made up of 2 distinct yet separate loop formations having 2 separate and distinct shoulders and also 2 deltas.
- Arches – Arches are encountered in only 5 percent of the patterns received. Arch patterns consist of ridges that run from one side of the pattern to the other. There is generally no delta. There are two types of arches – Plain arches and Tented arches.
- Whorl Tracings – There are essentially two different components to a whorl classification – the first is the pattern and the second is the tracing. To find a whorl tracing you must identify the left delta.
These are the different types of fingerprint patterns that have been firmly established by fingerprint examiners and experts all over the world.
Types of Fingerprints
There are three main types of fingerprints:
i) Visible prints or Patent Print.
- Latent prints
- Impressed prints or Plastic Print.
Visible prints are also called patent prints and are left in some medium, like blood, that reveals them to the naked eye. They can be when blood, dirt, ink or grease on the finger come into contact with a smooth surface and leave a friction ridge impression that is visible without development.
Latent prints are not apparent to the naked eye. They are formed from the sweat from sebaceous glands on the body or water, salt, amino acids and oils contained in sweat. The sweat and fluids create prints must be developed before they can be seen or photographed. They can be made sufficiently visible by dusting, fuming or chemical reagents.
Impressed prints are also called plastic prints and are indentations left in soft pliable surfaces, such as clay, wax, paint or another surface that will take the impression. They are visible and can be viewed or photographed without development.
Now that we have categorized the various types of fingerprints, let's determine if we were crime scene investigators, could we differentiate among the fingerprint types? If you were a crime scene investigator or an investigator of a scene of interest, what type of fingerprints would you have discovered in these cases?
A Hershey's chocolate bar
A bloody print on a knife
A baseball helmet
The correct answers are:
Plastic prints because the chocolate bar softens when held and the ridges of the finger are present and visible to the naked eye.
Patent prints because a foreign substance, namely blood, has left a visible impression on an object, namely the knife, which is visible to the naked eye.
Latent prints because the helmet must be examined and the surface of the helmet technologically enhanced in order for the fingerprints to be viewed. Some techniques available to provide for identification of these types of prints are lasers, powders and various light sources.
The knowledge of the different types of fingerprints is invaluable to investigators in their quest to identify the source of the fingerprints, and the science of fingerprints is fascinating to the lay person. For investigators, fingerprints can provide invaluable clues as they serve as a means of identifying the source of the print. Because the seasoned investigator has a thorough knowledge of the different types of fingerprints, he is able to recover them for use as evidence or for other purposes.
DNA fingerprinting is a very useful way that police and other law enforcement agencies find a criminal. DNA fingerprinting can also be called DNA profiling. A DNA profile is made by using blood and other body substances taken from a crime scene. Every individual has unique DNA. While you can change your appearance, you can't change your DNA. Because of this, scientists are starting to use DNA analysis to link suspects to blood, hair, skin and other evidence left at crime scenes. DNA fingerprinting is done by isolating the DNA from human tissues. The DNA is cut using special enzymes, sorted and passed through a gel. It's then transferred to a nylon sheet, where radioactive probes are added to produce a pattern -- the DNA fingerprint.
Every time a new Osama bin Laden tape comes out, the FBI Audio Lab in Quantico,Va. runs it through a voice analyzer, which captures the frequency, intensity and other measurements to determine whether the tape is authentic. These so-called "voice fingerprints" aren't as definitive as fingerprints or DNA, but they can help distinguish one person from another.
The Fingerprinting Process
The technique of fingerprinting is known as dactyloscopy. Until the advent of digital scanningtechnologies, fingerprinting was done using ink and a card.
To create an ink fingerprint, the person's finger is first cleaned with alcohol to remove any sweatand dried thoroughly. The person rolls his or her fingertips in ink to cover the entire fingerprint area. Then, each finger is rolled onto prepared cards from one side of the fingernail to the other. These are called rolledfingerprints. Finally, all fingers of each hand are placed down on the bottom of the card at a 45-degree angle to produce a set of plain (or flat) impressions. These are used to verify the accuracy of the rolled impressions.
Today, digital scanners capture an image of the fingerprint. To create a digital fingerprint, a person places his or her finger on an optical or silicon reader surface and holds it there for a few seconds. The reader converts the information from the scan into digital data patterns. The computer then maps points on the fingerprints and uses those points to search for similar patterns in the database.
Can your fingerprints be changed -- or stolen?
A minor scrape, scratch or even burn won't affect the structure of the ridges in your fingerprints -- new skin reforms in its original pattern as it grows over the wound. But each ridge is also connected to the inner skin by small projections called papillae. If these papillae are damaged, the ridges are wiped out and the fingerprint destroyed.
Some criminals have tried to evade capture by tampering with their own fingerprints. Chicago bank robber John Dillinger reportedly burned his fingertips with acid in the 1930s. Recently, a man in Lawrence, Mass., tried to hide his identity by cutting and stitching up all ten of his fingertips (fortunately, a police officer recognized his face).
But as fingerprint technology becomes a common form of authentication from bank vaults to luxury cars, law enforcement officials worry that would-be criminals might try to steal entire fingers for the prints. In one case, robbers in Malaysia cut off a man's fingers so they could steal his Mercedes. Companies that make biometrics security equipment realize the potential dangers of this system, and are now creating scanners that detect blood flow to make sure the finger is still alive.
Modern Fingerprinting Techniques
The Henry system finally enabled law enforcement officials to classify and identify individual fingerprints. Unfortunately, the system was very cumbersome. When fingerprints came in, detectives would have to compare them manually with the fingerprints on file for a specific criminal (that's if the person even had a record). The process would take hours or even days and didn't always produce a match. By the 1970s, computerswere in existence, and the FBIknew it had to automate the process of classifying, searching for and matching fingerprints. The Japanese National Police Agency paved the way for this automation, establishing the first electronic fingerprint matching system in the 1980s. Their Automated Fingerprint Identification Systems (AFIS), eventually enabled law enforcement officials around the world to cross-check a print with millions of fingerprint records almost instantaneously.