Warm-Up September 29, 2014

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Warm-UpSeptember 29, 2014

1. What causes fingerprints? Can they be altered?

2. What makes fingerprints unique?


Objective

• SWBAT compare fingerprint detection techniques.


Agenda

1. Crime 360

2. Types of Fingerprints

3. Fingerprint Detection

4. Fingerprint Detection Videos

5. Henry Classification System

6. AFIS/FBI Article

7. Frontline Real CSI

8. Exit Slip

T. Trimpe 2008 http://sciencespot.net/

Anderson CooperCSI Effect – Hairs & Fibers

1. What crime lab did the reporter visit?A. Chicago B. New York C. Las Vegas

2. How many hairs did the investigator use to help in getting a conviction in the kidnapping/homicide case? A. 3 B. 30 C. 300

3. True or False? Real crime labs tend to be darker to make it easier to see evidence.

4. True or False?It is easy to match any hair found at a crime scene to a specific person.

5. What must be present in a hair sample to test for nuclear DNA?A. Shaft B. Cuticle C. Root

Watch the video and then answer the questions.Video Link: https://www.youtube.com/watch?v=fGc4PaLB-ek

https://www.youtube.com/watch?v=fGc4PaLB-ek

https://www.youtube.com/watch?v=fGc4PaLB-ek

1. What crime lab did the reporter visit?A. Chicago B. New York C. Las Vegas

2. How many hairs did the investigator use to help in getting a conviction in the kidnapping/homicide case? A. 3 B. 30 C. 300

3. True or False? Real crime labs tend to be darker to make it easier to see evidence.

4. True or False?It is easy to match any hair found at a crime scene to a specific person.

5. What must be present in a hair sample to test for nuclear DNA?A. Shaft B. Cuticle C. Root

The answers are …


Types of Fingerprint Patterns

There are 3 basic fingerprint patterns

– loops

(60-65% of population) – whorls

(30-35%)– arches

(5%)


Loops• Have ridges entering from one side of the print, turning, and leaving from the same side.

• The pattern area of the loop is surrounded by two diverging ridges known as type lines.

• The approximate center is called the core.

• The ridge point nearest the type line divergence is known as the delta (capital greek letter Δ).


Loops

• 65% of the population have loops.

• All loops must have one delta.

• If the loop opens toward the little finger then it is a ulnar loop.

• If the loop opens towards the thumb then it is a radial loop.


Arches

• In an arch, ridges enter from one side of the print and exit on the opposite side.


Arches

• Arches are divided into two distinct groups: – plain arches – tetrarches or tented

arches

• The tetrarch consists of an upthrusted ridge in the center of the arch.


Whorls

• All whorl patterns must have a core and at least two deltas


Special Loops

• The double loop is made up of two loops combined into one fingerprint.

• The pocked loop has a small circle at the core.


Other Patterns

• An accidental pattern contains two or more patterns, but not the plain arch, and is not covered by other categories.

• It may consist of a combination loop and plain whorl or loop and tented arch.

It’s time to makesome prints!

Avoid Partial Prints

GOOD PRINTGet as much of the top part of your finger as possible!

Directions

1st – 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!

2nd – 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.

3rd – Continue this process to make a fingerprint of all ten fingers on the “My Prints” worksheet.

4th –Use your notes 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

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

1Introduction to Basic Ridgeology by David Ashbaugh, May 1999 Image from http://www.cs.usyd.edu.au/~irena/minutia.gif

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.

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.

Fingerprint IdentificationWhen 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)

http://www.fdle.state.fl.us/CrimeLab/images/fingerrint%20comparison%20for%20afis.jpg

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.

Rid

ge C

har

acte

rist

ics

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

http://cnx.org/content/m12574/latest/properties.jpg

Ridge Characteristics

Crossover

Core

Bifurcation (fork)

Ridge ending

Island

Delta

Pore

Scar

EXAMPLE

http://www.dkfz.de/tbi/projects/bmcv/images/iu_it246_04s_fingerprint1.jpg

How many ridge characteristics can you identify in this fingerprint?

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.

Try It!

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

Identify each fingerprint pattern.

?A B

CD E

Right Hand

Left Hand

Left Hand

Right Hand

Right Hand


Types of Prints• Latent: hidden or invisible

– Made by natural body secretions of the hands and fingers (perspiration & grease)

– Requires dusting or other method to make visible

• Patent: visible to the naked eye– Blood, ink, dirt, glass

• Plastic: a 3-D fingerprint– Wet paint– Soft material like clay


Impressions and Prints

• Impression– 3-D– in soft surface– often visible

• Print– 2-D– transfer of skin perspiration, oils, or a foreign

substance– usually latent


Powder Techniques• Used on non-absorbent surfaces

• Tipped or very softly brushed on

• Various types

• Black powder (carbon)

• Grey powder (Aluminum dust)

• Magnetic-Sensitive Powder (Magnabrush)

• Fluorescent Powder (seen in UV light)

http://www.youtube.com/watch?v=BZNXFbG-ux4


Using Powder with a Brush• Powder is brushed on carefully with a twirling motion.

• The excess powder is removed with the brush or a puffer bulb.

• Prints are photographed in place before lifting.

• Lift the print with broad adhesive tape.

• Transfer the print by sticking tape onto a card or lifter.


Chemical Techniques

• Iodine Fuming • Ninhydrin• DFO• Silver Nitrate• Physical developer• Super Glue Fuming


Iodine Fuming• Oldest technique for latent prints

• Iodine crystal sublimes in Fuming Cabinet

• Iodine reacts with fatty oils or perspiration (salts)

• Print fades rapidly

• Fixed by spraying with starch solution (blue)

http://www.youtube.com/watch?v=XLvZkx7HEEA


Ninhydrin• Ninhydrin (triketohydrindene hydrate)

• For latent prints on paper & porous surfaces

• Interacts with amino acids in proteins in fingerprints

• Easy to use & sensitive

• Sprayed on

• Prints appear in 1-2 hours, weak prints in up to 48 hours, hastened by heat.

http://www.youtube.com/watch?v=fF_v-MymoOk


Frontline Real CSI

1. What is the Real CSI?

2. Who did the fingerprint match that was found in Madrid?

3. What is the scientific premise for fingerprints?

4. What is the standard for points of comparison for fingerprints?

5. What unique characteristics are looked at in a fingerprint?

6. Who did the fingerprint really belong to?


Homework

• Fingerprinting Pre-Lab Questions due Tuesday


Exit SlipSeptember 29, 2014

1. Get out a mobile device or use one of the computers and go to m.socrative.com. You can also use one of the iPads that has the Socrative app.

2. When prompted, enter 417101 for the room number.

QUESTION: How does a crime scene specialist detect latent prints and decide how to process them?

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Warm-Up September 29, 2014

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