Fingerprinting Part 3-Galton Details Today’s Lesson Question: How can fingerprints be individualized?

Students will be able to: 1)Identify individual characteristics (Galton details) in a fingerprint pattern Today’s Objectives

FINGERPRINTS AS EVIDENCE Why are fingerprint patterns (loop, arch, whorl) considered class evidence? FINGERPRINTS AS EVIDENCE

Levels of Fingerprinting Classification The 3 levels of fingerprint classification: 1) pattern matching (a class characteristic), 2) Galton details, and 3) ridge patterns (#2 and #3 can both be used to individualize a print).  Levels of Fingerprinting Classification

The ridges of friction skin are not continuous, but rather, contain numerous interruptions – the Galton details. These details are more commonly called "characteristics" or "points of identity" and consist of three basic types: 1)ridge endings 2)bifurcations (a ridge that divides) 3)Dots (or islands) These "characteristics" or "points" are randomly scattered during friction ridge skin formation and their position, like all components of friction ridge skin, are not duplicated from one individual to the next or from one finger to the next. Though a predetermined minimum number of points are not required in order to make an identification, the Galton details are usually instrumental when an identification is made. The Galton Details

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 Crossover Core Bifurcation (fork) Ridge ending Island Delta Pore Scar EXAMPLE http://cnx.org/content/m12574/latest/properties.jpg

Try It! Students will identify as many Galton details as possible on the worksheet.

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