Forensic Science T Trimpe 2006 http sciencespot net

Forensic Science T. Trimpe 2006 http: //sciencespot. net

Historical Development 1. 3 rd century B. C. in China—oldest known documents 2. Ancient Babylon (1792 -1750 B. C. )—fingerprints pressed into clay tablets marked contracts 3. 1684—Dr. Nehemiah’s paper describes the patterns on human hands, including the presence of ridges 4. 1788—Johann Mayer noted that the arrangement of skin ridges is never duplicated in two persons 2

Historical Development 5. 1823—Jan Evangelist Purkyn describes nine fingerprint patterns 6. 1856—Sir William Herschel (right) began the collection of fingerprints and noted they were not altered by age 7. 1883—Alphonse Bertillon created a way to identify criminals that were repeat offenders 3

Historical Development 8. 1888—Sir Francis Galton (r) and Sir Edmund Richard Henry developed the fingerprint classification system still used in the US 9. 1891—Iván (Juan) Vucetich collected all ten fingerprint impressions and noted measurements 10. 1896—Sir Henry, with two colleagues, created a system that divided fingerprints into groups. All ten fingerprints are imprinted on a card (called a ten card) along with other notations 4

Example of a Ten Card 5

What Are Fingerprints? • All fingers, toes, feet, and palms are covered in small ridges • Ridges help us grip objects • Ridges are arranged in connected units called dermal, or friction, ridges • Fingers accumulate natural secretions and dirt • Fingers leave create prints on objects we 6 touch

Structure of Skin 7

Formation of Fingerprints • Skin consists of: – Inner layer—dermis – Outer layer—epidermis – Basal layer in between • Basal layer grows faster than the layers above and below it • Basal layer collapses and folds to form intricate shapes • Fingerprints begin forming near the 10 th week of pregnancy 8

Fingerprint Principles According to criminal investigators, fingerprints follow 3 fundamental principles: • A fingerprint is an individual characteristic; no two people have been found with the exact same fingerprint pattern. • A fingerprint pattern will remain unchanged for the life of an individual; however, the print itself may change due to permanent scars and skin diseases. • Fingerprints have general characteristic ridge patterns that allow them to be systematically identified.

Fingerprint Classes There are 3 specific classes for all fingerprints based upon their visual pattern: arches, loops, and whorls. Each group is divided into smaller groups as seen in the lists below. Arch Plain arch Tented arch Loop Radial Loop Ulnar loop Whorl Plain whorl Central pocket whorl Double loop whorl Accidentical

Interesting Info Fingerprint Factoid: 60% of people have loops, 35% have whorls, and 5% have arches Did you know? Dactyloscopy is the study of fingerprint identification. Police investigators are experts in collecting “dactylograms”, otherwise known as fingerprints.

Characteristics of Fingerprints • Forensic examiners look for – Core (the center of a whorl or loop) – Deltas (triangular regions near a loop) • Ridge count – Counting from the core to the edge of the delta – Distinguishes one fingerprint from another 12

Characteristics of Fingerprints • Basic patterns can be further divided: – Arch patterns: • 4% plain • 1% tented – Whorl patterns: • 2% central pocket • 4% double loop • 0. 01% accidental 13 • Even twins have unique fingerprints

Characteristics of Fingerprints 14

Arches are the simplest type of fingerprints that are formed by ridges that enter on one side of the print and exit on the other. No deltas are present. Spike or “tent” Plain Arch Ridges enter on one side and exit on the other side. Tented Arches Similar to the plain arch, but has a spike in the center.

Left Hand Loops must have one delta and one or more ridges that enter and leave on the same side. These patterns are named for their positions related to the radius and ulna bones, i. e. the bone the loop opening is facing towards. Ulna Radius Delta L – Radial Loop R - Ulnar Loop L – Ulnar Loop R - Radial Loop X-Ray Imagine: http: //www. tooloop. com/wp-content/uploads/2013/12/Radius-Ulna-X-Ray. jpg

Whorls have at least one ridge that makes (or tends to make) a complete circuit. They also have at least two deltas. If a print has more than two deltas, it is most likely an accidental. Plain Whorl Central Pocket Whorl Draw a line between the two deltas in the plain and central pocket whorls. If some of the curved ridges touch the line, it is a plain whorl. If none of the center core touches the line, it is a central pocket whorl.

Characteristics of Fingerprints 18

Whorls – Part 2 Double Loop Whorl Accidental Whorl Delta Double loop whorls are made up of any two loops combined into one print. Accidental whorls contain two or more patterns (not including the plain arch), or does not clearly fall under any of the other categories.

Identify each fingerprint pattern. Right Hand Left Hand

It’s time to make some prints! Avoid Partial Prints GOOD PRINT Get as much of the top part of your finger as possible!

Directions 1 st – Roll the “pad” portion of your thumb over the ink pad from the left side of your thumb to the right. You do not have to push down really hard! 2 nd – Roll the “pad” portion of your thumb from the left side of your thumb to the right in the correct box on your paper to make a thumbprint. 3 rd – Continue this process to make a fingerprint of all ten fingers on the “My Prints” worksheet. 4 th –Use your notes and a magnifying lens to help you figure out what type of pattern is found in each of your fingerprints. Label each one with the pattern’s name.

A Closer Look at Fingerprints 8 th Grade Forensic Science Image from ftp: //sequoyah. nist. gov/pub/nist_internal_reports/ir_6534. pdf T. Trimpe 2007 http: //sciencespot. net/

Ridgeology: The study of the uniqueness of friction ridge structures and their use for personal identification. 1 As we have learned in our first lesson, a fingerprint is made of a series of ridges and valleys on the surface of the finger. The uniqueness of a fingerprint can be determined by the pattern of ridges and valleys as well as the minutiae points, which are points where the ridge structure changes. The koala is one of the few mammals (other than primates) that has fingerprints. In fact, koala fingerprints are remarkably similar to human fingerprints; even with an electron microscope, it can be quite difficult to distinguish between the two. 1 Introduction to Basic Ridgeology by David Ashbaugh, May 1999 Image from http: //www. cs. usyd. edu. au/~irena/minutia. gif

Fingerprint Identification When minutiae on two different prints match, these are called points of similarity or points of identification. At this point there is no international standard for the number of points of identification required for a match between two fingerprints. However, the United Kingdom requires a minimum sixteen points while Australia requires twelve. Automated Fingerprint Identification System (AFIS) AFIS is a computerized system capable of reading, classifying, matching, and storing fingerprints for criminal justice agencies. Quality latent fingerprints are entered into the AFIS for a search for possible matches against the state maintained databases for fingerprint records to help establish the identity of unknown deceased persons or suspects in a criminal case. http: //www. fdle. state. fl. us/Crime. Lab/images/fingerrint%20 comparison%20 for%20 afis. jpg

Ridge Characteristics Use these characteristics as points of identification when comparing fingerprint samples. The more points you can find in common, the better the match!

Ridge Characteristics A X E E L MP Crossover Core Bifurcation (fork) Ridge ending Sca r Island Delta Pore http: //cnx. org/content/m 12574/latest/properties. jpg

How many ridge characteristics can you identify in this fingerprint? http: //www. dkfz. de/tbi/projects/bmcv/images/iu_it 246_04 s_fingerprint 1. jpg

Try It! 1 – Blow up your balloon about halfway and twist the end to keep the air from coming out. Do not tie it off! 2 – Use an ink pad to make a print with all of your fingers and label each one with a permanent marker. Write your name on the balloon as well. 3 – Blow up the balloon to full size and tie the end. 4 – Analyze the fingerprints to find several ridge structures that we have discussed. Use a highlighter to mark these structures on your “My Prints” worksheet. Think About It! Which ridge structures were most common in your fingerprints? Which ridge structures were most common in your group? Were there any structures that were not found in any of the fingerprints? Balloon Fingerprint Activity: http: //www. msichicago. org/fileadmin/Education/learninglabs/lab_downloads/fingerprint_analysis. pdf

Forensic Science T. Trimpe 2007 http: //sciencespot. net/

Types of Fingerprints There are 3 types of prints that investigators look for at crime scenes: 1. Patent fingerprints—visible prints transferred onto smooth surfaces by blood or other liquids 2. Plastic fingerprints—indentations left in soft materials such as clay or wax 3. Latent fingerprints—made visible by dusting with powders or the use of chemicals 31

Latent prints are impressions left by friction ridge skin on a surface, such as a tool handle, glass, door, etc. Prints may be collected by revealing them with a dusting of black powder and then lifted with a piece of clear tape. Did you know? Camel hair is the most common animal hair used to make fingerprint brushes. Now many brushes (like the one above) are made out of fiberglass.

Some investigators use fluorescent powder and UV lights to help them find latent prints on multi-colored or dark surfaces. Magnetic powder can also be used to reveal latent prints. This type of powder works better on shiny surfaces or plastic baggies or containers. The cyanoacrylate fuming method (often called the super glue method) is a procedure that is used to develop latent fingerprints on a variety of objects. Ninhydrin is a chemical that bonds with the amino acids in fingerprints and will produce a blue or purple color. It is used to lift prints from surfaces such as paper and cardboard. Click the icon to view the Crime 360 Super Glue Video Top Left: http: //www. stapletonandassociates. com/images/Mag. Powder. jpg Bottom Left: http: //www. ok. gov/osbi/images/ninhydrin%20 print. jpg Bottom Right: http: //www. forensicsrus. com/images/Superglue. Print. jpg

Fingerprint Forensic FAQs • How are latent fingerprints collected? 34

Fingerprint Forensic FAQs • Can fingerprints be erased? Only temporarily; they will grow back if removed with chemicals • Is fingerprint identification reliable? Yes, but analysts can make mistakes • Can computers perform matches in seconds? No, but the FBI’s Integrated Automated Fingerprint Identification System (IAFIS or AFIS) can provide a match in 2 hours 35

The Future of Fingerprinting • New scanning technologies – Yield detail in minute patterns – Reduce analytical mistakes – Analyze trace elements of objects on the skin • Technologies that recognize patterns in – Retina – Face – Veins in your palm 36