Warm Up Objective: Scientists will describe fingerprints and their use by analyzing their own fingerprints. What is the topic? What will you be doing? Why is this important? How will you know if you have done well?

Warm Up Objective: Scientists will describe fingerprints and their use by analyzing their own fingerprints. What is the topic? Fingerprints and their use What will you be doing? Analyzing fingerprints Why is this important? Evidence for convictions; future career choice How will you know if you have done well? Able to describe fingerprints and use; analyzed fingerprint

History of Fingerprints Ancient Babylon (1750 B.C.) Fingerprints pressed into clay tablets marked contracts. Third century B.C. China Contract documents showing fingerprints 1788, Johann Mayer Noted that the arrangement of skin ridges is never duplicated in two persons. The first scientist to recognize this fact.

What Are Fingerprints? All fingers, toes, feet, and palms are covered in small ridges. These ridges are arranged in connected units called dermal, or friction, ridges. Ridges help us get or keep our grip on objects. Natural secretions plus dirt on these surfaces leave behind an impression (a print) on those objects with which we come in contact.

PRINCIPLES OF FINGERPRINTS There are 3 fundamental principles: 1) Individual characteristic No two people have been found with the exact same fingerprint pattern. 2) Pattern will remain unchanged for the life of an individual The print itself may change due to permanent scars and skin diseases. 3) General characteristic ridge patterns that allow them to be systematically identified.

Fingerprint Characteristics Forensic examiners look for the presence of a core (the center of a whorl or loop) and deltas (triangular regions near a loop). Delta

Types of Fingerprints There are 3 general fingerprint distinctions: Arches Loops Whorls

Arches 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. 2 types: plain arch & tented arch Tented Arches Similar to the plain arch, but has a spike in the center. Spike or “tent” Plain Arch Ridges enter on one side and exit on the other side.

Arches

Radius Ulna Left Hand Loops 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. Types Radial—opens toward the thumb Ulnar—opens toward the “pinky” L – Ulnar Loop R - Radial Loop L – Radial Loop R - Ulnar Loop

Loops

Whorl 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. Whorls have at least two deltas and a core. 4 Types Plain Central Pocket Double Loop Accidental

Plain Whorl Two Deltas One Core Displays a degree of symmetry bsapp.com

Central Pocket Loop Two Deltas One Core Lacks Symmetry A delta is often observed near the core

Whorls – Part 2 Accidental Whorl Double Loop Whorl Double loop whorls are made up of any two loops combined into one print. Delta Accidental Whorl Accidental whorls contain two or more patterns (not including the plain arch), or does not clearly fall under any of the other categories. 15

Double Loop Two Deltas Two Cores Appears to have an “S” in the print

Accidental All other prints bsapp.com

Fingerprint Balloon Blow up your balloon about halfway and twist the end to keep the air from coming out. Do NOT tie it off yet! 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. Blow up the balloon to full size and tie the end Let it dry! Identify the ridge pattern for each finger and thmb Using the ridge characteristics paper, identify them on your balloon by circling and labeling. Try to find as many as you can!

Analysis What type of fingerprints do you have? How do you know? (What minutiae did you use?) How can fingerprinting be useful?