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
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.
Radial Loop (Right Thumb)
Loop opens toward the left or the radial bone.
Ulnar Loop (Right Thumb)
Loop opens toward right or the ulna bone.
Delta
NOTE: On the left hand, a loop that opens to the left would be an ulnar loop, while one that opens to the right would be a radial loop.

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 C
Right Hand E D
Right Hand
Left Hand

10. Other Systems of Identification
DNA- can be extracted from saliva, blood, semen, or hair
Dental Records
Handwriting
Voice Analysis
Note: None of these are as conclusive as fingerprints!!!

11. Fingerprinting in Animals
Koala Bears have prints strikingly similar to humans
Horses are identified by their snout
Whales are identified by their fluke

12. Fingerprint Files
The Department of Justice began a fingerprint file in the early 1900’s
The FBI began a fingerprint file in 1930, which is now considered to be the largest collection of fingerprints in the world

13. Removing Fingerprints From the Crime Scene
Most commonly, latent prints are recovered from the scene of a crime
Latent prints are prints left by the oils in your skin that are invisible to the unaided eye
They need to be lifted in order to be visualized

14. Types of Prints
Visible Prints: These are found when the finger deposits a visible material such as ink, dirt, or blood onto a surface
Plastic Prints: This occurs when a fingerprint in impressed into a soft surface such as clay, soap, wax, or dust.
Latent Prints: These prints are usually invisible to the unaided eye and are caused by depositing oil on surfaces that are touched

15. Lifting Latent Prints Absorbent Surfaces Non Absorbent Surfaces
These prints need to be fumed using superglue, iodine, or physical developer
The chemicals react with the oils in the skin when heated in a chamber to visualize the print
Examples of surfaces that are fumed: clothing, paper
These prints can be dusted with powder and a brush and lifted with tape
Examples of surfaces that are dusted: wood (table, chairs), glass (windows, tableware), plastic, metal (shotgun, knife, doorknob)

16. A closer look at fuming Iodine Fuming Physical Developer Superglue
This is the oldest method of fuming. It was discovered on accident. When Iodine is heated it goes directly from a solid to a gas (sublimation). The Iodine crystals combine with the oils to visualize the print.
This method requires Silver Nitrate and is shown effective for developing latent prints on porous articles that might have been wet at one time.
Superglue is now the most common method for developing prints. Superglue contains 99% of the chemical Cyanoacrylate Ester. This chemical interacts with the oils to visualize a print.

17. Formation of Fingerprints
Fingerprints are formed before birth, during the development of the hands. Fingerprints aren't actually formed in the skin, but are caused by ridges in the flesh underneath the skin.
Genetics plays some part in their formation, but even identical twins (who have identical DNA) have different fingerprints.
Fingerprints are formed on an fetus at about 5 months into the gestation.

18. Can a person change or remove their fingerprints?
YES NO
Very difficult to remove all ridge characteristics
You would have to remove 5 of the 7 layers of the epidermis to damage the fingerprint pattern
People have tried burning in acid, using metal files, skin grafting
Nearly impossible to remove them entirely
Even burning in corrosive acid can still leave fingerprint patterns undamaged in spots
To identify a print police need to match at least 12 minutae points.

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

20. 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 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.