“Fingerprints cannot lie, but liars can make fingerprints” - proverb

In this chapter you will learn… Why fingerprints are individual evidence Why there may be no fingerprint evidence at the crime scene How computers have assisted the process To recognize general ridge patterns Explain the difference between visible, latent, and plastic fingerprints Develop latent prints using physical and chemical methods

Fingerprint Portfolio 3-ring folder Keep/collect fingerprints recorded through various methods

Fingerprints Recording Prints – kept for comparison rolling inked prints primary identification number FBI has national database called AFIS Lifting Prints – retrieved from the scene Black, white and fluorescent powder Chemicals—ninhydrin, iodine, silver nitrate, cyanoacrylate Other Types of Prints – can be individualized too! Palm, lip, teeth, eye, ear, voice, shoe and footprints

3 Principles of Fingerprints 1. A fingerprint is an individual characteristic 2. A fingerprint remains unchanged during an individual’s lifetime 3. Fingerprints have general ridge patterns that allow them to be systematically classified

Principle #1 Probability of 2 people with same prints is very small Supported by theory & practice FBI has nearly 50 million records Individuality determined by study of Ridge characteristics known as minutiae Average print contains 150 individual ridge characteristics No basis for how many are needed to identify

Principle #2 Dermal Papillae Develop during 6th week Helps provide firmer grasp and resistance to slippage Fingerprints leave behind perspiration and oils, leaving a latent print Dermal papillae – determines ridges Dermal Papillae

Principle #2 Prints remain unchanged throughout life Wounds must penetrate 1-2 mm beneath surface to scar prints (must reach dermal papillae) John Dillinger – paid a doctor $5000 to dissolve his prints with corrosive acid – not successful

Principle #3 – 3 class division Arch Loop Whorl 5% 65% 30% Population Breakdown by %

Arch Plain Arch An arch has friction ridges that enter on one side of the finger and cross to the other side while rising upward in the middle. They do NOT have type lines, deltas, or cores. Types Plain Tented Exit here Enter here

Arch Plain Arch Tented Arch Arch not as high Arch higher in center

Loop A loop must have one or more ridges entering and exiting from the same side. Loops must have one delta. Types Radial—opens toward the thumb Ulnar—opens toward the “pinky” (little finger) Which type of loop is this, if it is on the right hand? Left hand? Delta Enter and exit from this side These are the same except which way they open

Loop Opens toward thumb Opens toward pinky

Whorl Core Whorls have at least two deltas and a core. A plain or central pocket whorl has at least one ridge that makes a complete circuit. A double loop is made of two loops. An accidental is a pattern not covered by other categories. Types Plain Central Pocket Double Loop Accidental Two Deltas

Whorl whorls have at least two deltas and a core. A plain or central pocket whorl has at least one ridge that makes a complete circuit. An accidental is a pattern not covered by other categories. A double loop is made of two loops.

Correctly Recording Prints Refer to handout/video

Ridge Characteristics Minutiae—characteristics of ridge patterns Ridge ending Short ridge Dot or fragment Bifurcation Double bifurcation Trifurcation Bridge Island Enclosure Spur

Fingerprint Minutiae

Primary Classification The Henry—FBI Classification Each finger is given a point value right left Allows all fingerprints to be classified into only 1024 categories

Primary Classification Assign the number of points for each finger that has a whorl and substitute into the equation: 16 8 4 2 1 right right left left left index ring thumb middle little + 1 = Left right right right left left thumb middle little index ring +1 16 8 4 2 1 That number is your primary classification number Right

Primary Classification Mr. Schatz’s Primary Classification is “goofball” right right left left left index ring thumb middle little + 1 1 ______ = 17 right right right left left thumb middle little index ring +1 16 This is one of the 1024 categories…Who else in this room is in my category?

Automated Fingerprint Identification Systems AFIS Computer system for storing and retrieving fingerprints Began in the early 1970’s to: Search large files for a set of prints taken from an individual Compare a single print, usually a latent print developed from a crime scene By the 1990’s most large jurisdictions had their own system in place. The problem - a person’s fingerprints may be in one AFIS but not in others IAFIS—the FBI’s Integrated Automated Fingerprint Identification system which is a national database of all 10-print cards from all over the country (1999)

AFIS

Types of Prints Plastic prints – indented or molded prints – made from pressing a finger into a plastic-like material to form a negative impression. Visible prints – left by a finger that has touched a colored surface such as blood, paint, ink, grease, mud or dust. Latent prints – invisible prints that must be developed by chemical or physical means.

Invisible prints that must be developed by chemical or physical means. Latent Prints Invisible prints that must be developed by chemical or physical means. Use a dusting powder or chemical means to develop the print Take pictures of print Lift the print when possible If you can’t lift the print…Recover the whole item the print is on and send to lab

Latent Prints The reason you get these prints is because you secrete different substances from your skin. Most secretions come from three glands: Eccrine (Sweat)—largely water, salts and amino acids (protein) Apocrine—secrete pheromones and other organic materials. Sebaceous—secrete fatty or greasy substances.

Developing Latent Prints Powders—adhere to both water and fatty deposits. Choose a color to contrast the background. Iodine—fumes react with oils and fats to produce a temporary yellow brown reaction. Ninhydrin—reacts with amino acids to produce a purple color. Silver nitrate—reacts with chloride to form silver chloride, a material which turns gray when exposed to light. Cyanoacrylate—“super glue” fumes react with water and other fingerprint constituents to form a hard, whitish deposit.

Partial Prints You do not need to lift a complete fingerprint to have sufficient ridge detail (minutia) present for an identification.

Documenting Prints Lift the print and put it on an index card Case Number Victim Information Incident Location Incident Date Recovering Officer Name Object or Location of Recovered Lift Method of Development Orientation if Needed Diagram where you found it Put all pertinent information on the card

Documenting Prints

Cyanoacrylate Fingerprints

Cyanoacrylate Chemistry Most super glue’s contain the chemical necessary to attach to the fingerprint remains Necessities: The container must be as airtight as possible A small heater is necessary to vaporize (boil) the Cyanoacrylate Water in the air helps the reaction to complete

More info… The boiling point of cyanoacrylate is thought to be somewhere between 120 – 150 degrees F The reaction can take time If left too long, results become poor

Ways to speed reaction time… Fume Circulation By using a fan and constantly circulating the air inside the chamber, the reaction becomes more efficient Chemical Acceleration Replace heat with sodium hydroxide added to super glue Water Vapor Method Introduce more water into the air Can be as simple as leaving container of water in the chamber

Fingerprint Test Fingerprint notes Classification system (given #’s) 3 principles of fingerprinting characterization Classification system (given #’s) Performance --- latent development

Chemical Development Iodine Fuming Ninhydrin Silver Nitrate Sublimation Does not last unless “fixed” Ninhydrin Useful for porous surfaces (paper) Silver Nitrate Reacts with salt Good for very old prints Must be done last

Silver Nitrate Development Mix (with popsicle stick) .85g of Silver Nitrate w/ 50ml distilled water Fingerprint a small part of an index card Drop card in and let sit for 5 minutes Remove and put in black light hood

Other Prints Ears—shape, length and width Voice—electronic pulses measured on a spectrograph Foot—size of foot and toes; friction ridges on the foot Shoes—can be compared and identified by type of shoe, brand, size, year of purchase, and wear pattern.

Other Prints Palm—friction ridges can be identified and may be used against suspects.

Other Prints Footprints are taken at birth as a means of identification of infants.

Other Prints Lips—display several common patterns Short vertical lines Short horizontal lines Crosshatching Branching grooves

Other Prints Teeth—bite marks are unique and can be used to identify suspects. These imprints were placed in gum and could be matched to crime scene evidence.

Other Prints The blood vessel patterns in the eye may be unique to individuals. They are used today for various security purposes.