People have been studying the unique characteristics and properties of fingerprints for thousands of years. In ancient Babylon, for example, clay impressions of fingerprints were used to seal business deals. Sir William Herschel is recognized as one of the first Europeans to begin collecting and studying fingerprints in the 1850s, which inspired others to do so as well.
However, fingerprint analysis didn't become common in crime-solving forensic science until the early 20th century. Here are some facts and tidbits about fingerprint forensics and how they came to be.
Dr. Jan Halamek, a professor at the University of Albany in New York, led a research team that came up with a test to determine a person's gender based on their fingerprints. Instead of examining size and shape, Halamek's test examines and analyzes the amino acid compounds in latent prints.
These fingerprints are created by sweat and natural oils, so heating the prints and applying a special chemical dye causes them to turn a specific color based on the concentration of amino acids left behind by the skin. Due to the fact females have more amino acids than males, Halamek claims the test is 99% effective.
A Commonly Used Fingerprint System Was Created By A Eugenicist
Sir Francis Galton, the man who may have coined the term "eugenics," is regarded as something of a fingerprint pioneer. An anthropologist and the cousin of biologist Charles Darwin, Galton was interested in the controversial idea that humans could be selectively bred to achieve desired traits. He theorized a person's fingerprints might be able to identify their racial characteristics or level of intelligence.
Galton's study of fingerprints led him to create a classification system called Galton's Details. The system identifies the raised ridges in a print based on five characteristics: the enclosure, the short ridge, the dot, the ridge ending, and the bifurcation. Modern-day investigators still study these details to determine whether or not two prints are alike.
The Pores In A Fingerprint Are Just As Important As The Ridges
French criminologist Edmond Locard began studying fingerprints back in 1910. Locard's specialty was poroscopy, which examined not only the ridges of a fingerprint but also the marks left behind by the pores in the skin. Several years later, Locard determined that if 12 points on two fingerprints match each other, then those prints are made by the same finger.
This standard is often still used to this day. However, a given country's legal system sets different standards for the number of matching points required to conclusively connect two fingerprints.
Fingerprint Evidence Comes In Three Different Types
People leave behind three different types of fingerprints that crime scene investigators look for: patent, latent, and plastic. Patent prints are easily visible and left by substances like blood, ink, dirt, and grease. If someone with a bloody hand touches a solid surface and leaves behind a print, that's a patent print. Latent prints aren't visible at all; they're made of the sweat and oils present on a person's hand. People leave latent prints behind all day long and never even think about it. These are the types of prints that are lifted at crime scenes using special powders and brushes.
In contrast, plastic prints are three-dimensional. These prints are made in paint, tar, soap, wax, and even clay. When law enforcement or crime scene techs process a crime scene and see patent or plastic prints, they simply take a picture of them, as they do not need to be processed in the same way as latent prints.
Francisca Rojas Was The First Person Prosecuted Using Fingerprint Evidence
In 1892, Francisca Rojas, a woman in Necochea, Argentina, murdered her two children and blamed it on a neighbor. Rojas was found wounded by the side of the road, so law enforcement initially sympathized with her and believed her story. However, they eventually discovered that she had set the murder in motion in an attempt to frame her neighbor, Pedro Ramón Velázquez, who she claimed was an ex-lover.
Rojas's ruse was uncovered after a bloody fingerprint was found on a door in her home. Since Rojas claimed she didn't touch the children once she found them dead, police believed the fingerprint had to belong to Velázquez. Ultimately, investigators discovered the print actually belonged to Rojas. Once she was confronted with the forensics, she confessed to the entire crime and went down in history as the first person found guilty through the use of fingerprint forensics.
A Pair Of Identical Criminals Made The Case For Fingerprinting Prisoners
For years, law enforcement primarily used the Bertillon system to keep track of prisoners' identities. This system was developed by French criminologist Alphonse Bertillon, who believed every person had a unique set of facial measurements (incidentally, this is where mugshots come from); however, this theory was debunked by two prisoners, William West and Will West, who not only had similar names but similar facial features.
When Will West entered a Leavenworth, KS, penitentiary in 1903, prison officials were immediately confused by his physical (and nominal) similarity to someone already incarcerated there. The two Wests weren't related, and they proved the Bertillon system wasn't foolproof. Their fingerprints, however, were unique. This was a key demonstration of fingerprints' effectiveness as an identification system for prisoners.
