Fingerprints

What are Fingerprints? Fingerprints are impressions of the ridges of the fingertips deposited on a surface in sweat or oil. No people have the exact same fingerprints due to the identity, number, and location of minutiae! They form from pressure on a baby's tiny, developing fingers in the womb during the 3 rd to 4 th month and NEVER change during one’s lifetime.

Fingerprint Removal To avoid law enforcement many people have tried to remove their fingerprints. John Dillinger In May 1934, John Dillinger, the infamous bank robber, hired a lawyer to put him in touch with two surgeons willing to perform plastic surgery on his face. The doctors performed the operation at Dillinger’s cabin hideout. The gangster flew into a rage when the bandages came off. He didn’t look any different. Enraged, Dillinger threatened to shoot the physicians then changed his mind when one of them suggested that he have his fingerprints burned off with acid. Dillinger liked the idea and following the painful dipping of his fingers into acid, it appeared that the process had worked. A few months later Dillinger was shot to death by FBI agents in Chicago. The medical examiner’s check of the body revealed that the bank robber’s fingertips were scarred. His old ridge patterns, however, were still visible. Even acid couldn’t remove fingerprints permanently.

Fingerprint Removal Roscoe Pitts Roscoe Pitts, a criminal from the 1940’s, had all ten fingers sutured to his chest for several weeks to cause growth of smooth skin on his fingertips.

Fingerprint Classifications In the 1890’s Sir Francis Galton conducted extensive research On fingerprints and convinced the English government to adopt fingerprints as an additional way to identify people. He proposed the three major pattern types which we today. Loops – 65%Arches – 5%Whorls – 30% There are several sub categories within each pattern.

Fingerprint Classifications Loops: Ridge line enters and exits from the same side. The side the ridge enters and exits determines it name. Ulna LoopRadial Loop Enters from thumbEnters from little finger

Fingerprint Classifications Arches: Ridges enter from one side of the finger and exit the other while riding upward in the middle. Plain ArchTented Arch

Fingerprint Classifications Whorls: Any other pattern not classified as Arch or Loop is a Whorl.

Fingerprint Classifications Name the fingerprint classifications (left hand). Arch Whorl Radial Loop Enters from thumb - Radial Enters from little finger - Ulna Ulna Loop Name the following (right hand): Whorl ArchUlna Loop Whorl

Ridge Classification Arches, loops, and whorls are the general patterns (class evidence). To make fingerprints individual we must look at the fine structure of ridge characteristics called minutiae. Common ridge characteristics Ending Ridge Bifurcation Bridge Enclosure or Island Spur Trifurcation Dot There are about 150 different ridge characteristics on a given print. The core is the approximate center of the pattern.

Ridge Classification Number and location of minutiae make fingerprints unique.

Types of Fingerprints Plastic Prints are made from pressing a finger into a material such: clay soap candle wax Visible Prints are made by touching a colored material such as: blood paint ink grease Latent Prints are essentially invisible and must be developed by chemical or physical means. they result from deposits of perspiration and body oils.

Visualizing Latent Prints Dusting used on nonporous surfaces

Visualizing Latent Prints Chemical Processes used on porous surfaces Super Glue FumingNinhydrin reacts with amino acids left by finger. turns latent print pink or orange. used on porous surfaces such as paper. reacts with print residue turning the print white.

Comparing Prints Despite technology a person still is needed to declare a match. Generally 8 – 14 points of similarity are needed to consider a match.

Modern Fingerprinting Techniques

What is AFIS? AFIS is an acronym for: Automated Fingerprint Identification System This system is maintained by the FBI's Criminal Justice Information Services Division. System can be accessed 24/7 by local law enforcement agencies.