1. Fingerprints
Forensic Science
T. Trimpe

2. 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.

3. 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

4. 60% of people have loops, 35% have whorls,
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.
ADD TO NOTES

5. 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.
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.

6. Loops
Radius
Ulna
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.
L – Radial Loop
R - Ulnar Loop
L – Ulnar Loop
R - Radial Loop
Delta
X-Ray Imagine:

7. Whorls
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.
Central Pocket Whorl
Plain 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.

8. Whorls – Part 2 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.

9. Identify each fingerprint pattern.? A B
Right Hand
Left Hand
Answer Key: A - Plain Whorl, B – Double Loop Whorl, C – Radial Loop, D – Tented Arch, E – Plain Arch C
Right Hand E D
Right Hand
Left Hand

10. ? A B C E D Double Loop Whorl Tented Arch Plain Arch Radial Loop
Plain Whorl A B
Right Hand
Left Hand
Tented Arch
Plain Arch
Answer Key: A - Plain Whorl, B – Double Loop Whorl, C – Radial Loop, D – Tented Arch, E – Plain Arch C
Right Hand E D
Radial Loop
Right Hand
Left Hand

11. A Closer Look at Fingerprints
Ridgeology
A Closer Look at Fingerprints
Image from ftp://sequoyah.nist.gov/pub/nist_internal_reports/ir_6534.pdf
T. Trimpe

12. 1. Ridgeology: is the study of the uniqueness of friction ridge structures and their use for personal identification.
2. 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.
Did you know?
1Introduction to Basic Ridgeology by David Ashbaugh, May Image from

13. 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.

14. 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.
AFIS Video Link:

15. 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!

16. Ridge Characteristics
Crossover
Core
Bifurcation (fork)
Ridge ending
Island
Delta
Pore
Scar
EXAMPLE

17. How many ridge characteristics can you identify in this fingerprint?

20. Let’s survey the class…
How do our fingerprint patterns compare to the expected averages?
Let’s determine their rate of occurrence…
How do our results compare to the averages?
60% - Loops % - Whorls % - Arches
__% - Loops __% - Whorls __% - Arches
Pattern #
Total Prints %
Arch
Loop
Whorl

21. Latent Prints
Forensic Science
T. Trimpe

22. How prints are left behind:
Ridges have small pores along their length
oils and sweat from pores leave a copy of the ridge marks

23. Type of prints found: Visible  ridges left in visible colour
(ex. from blood or paint)
Plastic  impressions left in soft materials
(ex. wax, soap)
Latent  invisible impressions left from oils and sweat

24. 1. Latent prints are impressions left by friction ridge skin on a surface, such as a tool handle, glass, door, etc.
2. Prints may be collected by revealing them with a dusting of black powder and then lifted with a piece of clear tape.
3. 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.

25. 4. Some investigators use fluorescent powder and UV lights to help them find latent prints on multi-colored or dark surfaces.
5. Magnetic powder can also be used to reveal latent prints. This type of powder works better on shiny surfaces or plastic baggies or containers.

26. Click the icon to view the Crime 360 Super Glue Video
6. 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.
7. During fuming the super glue heats up and attaches to the amino acids in the fingerprint.
The evidence is placed in a super glue chamber to develop the prints.
Click the icon to view the Crime 360 Super Glue Video
8. 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.

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

28. Directions to create Ink Prints
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 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.

29. Try It on a balloon!
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:

30. Directions for lifting Latent Prints:
1 - Cover your table with white butcher paper or newspaper. You must dust everything on the paper!
2 - Get a lifting kit from your teacher that contains black powder, brushes, and clear tape.
3 - Press the pad of your right thumb on a CD or glass slide to make a print. Place on the paper covering your table.
4 – Dip a brush lightly into the container of black powder and then tap off the extra on the lid. You only need a very small amount of powder to dust the print.
5 – Hold the brush over the print and rotate it between your thumb and fingers. Use the brush to remove any extra powder.
6 - Use a small piece of clear tape to lift the print and place it in the box on your worksheet.
CAUTION: The black powder will be messy and isn’t easy to clean up. Don’t dust anything without permission!

31. Clean Up
1 – Clean off the CDs or glass slides and put them back in the kit with the brushes and tape.
2 – Have someone help you fold the paper in half and tap it to return the extra black powder to the container.
3 – Put the black powder in the box and have it checked in by your teacher.
4 – Get a towel and “dry” wash the table – especially the edges that weren’t covered with paper.
5 – Get a wet towel to wash off the table and then wipe it with some dry towels. Keep cleaning until all the black powder is off the table!