1. FORENSIC SCIENCE Fingerprints

2. History
3000 years ago: Chinese used fingerprints to sign legal documents
1892 – Galton describes loops, whorls, and arches
1897 – Sir Edward Henry develops the classification system that is used in the U.S.
1924 – FBI Identification Division Established

3. What is a fingerprint?
A fingerprint is a friction skin ridge found on the palm side of the fingers and thumbs.
Similar friction skin ridges can be found on the surface of the palms and the soles of feet.
These skin surfaces are designed to provide a firmer grasp and resistance to slippage.

4. Dactyloscopy: The study of fingerprints
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.

5. What are prints used for?
A variety of purposes including:
Solving crimes
Identity confirmation (passport, cashing checks, etc.)
Determining the identity of the deceased
Entrance control for buildings and rooms
Clearance for employment

6. Automated Fingerprint Identification System
AFIS
Automated Fingerprint Identification System
AFIS is one of the three significant electronic databases for law enforcement purposes.
There are two types of files:
Knowns: Contains prints of known individuals
Forensic files: Consists of images from unsolved cases

7. IAFIS
By the 1990’s most large jurisdictions had their own system in place. The problem - a person’s fingerprints may be in one AFIS but not in others
IAFIS—the FBI’s Integrated Automated Fingerprint Identification system which is a national database of all 10-print cards from all over the country

8. In Court
When minutiae on two different prints match, these are called points of similarity or points of identification.
Courts require different amounts of matching points of minutia
UK requires 16 points
Australia requires 12 points
FBI requires 12 points
U.S. courts require 6-8 points

9. Primary Classification
The Henry—FBI Classification
Each finger is given a point value
left
right

10. 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

11. 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.
Plain Arch
Ridges enter on one side and
exit on the other side.

12. 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.
L – Radial Loop
R - Ulnar Loop
L – Ulnar Loop
R - Radial Loop
Delta

13. 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.

14. 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.

15. 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

16. Numbers Assigned to Digits for a Tenprint

17. Factors Affecting Fingerprints
Negative affects:
Allowing subjects to “print themselves”
Excessive pressure
Not enough pressure
Perspiration, or wet fingers
Sickness and disease
Trade & Industrial Education

18. Taking a Tenprint
Start with finger level to surface of ink pad and at the edge of the nail
Roll finger over ink pad to the opposite side of the nail, without pressing down
Roll finger level to surface and at the edge of the nail onto the Tenprint card to the opposite side of the nail, without pressing down.
Print should be wide and not resemble typical finger sizes

19. Class Analysis
Find the statistics for loops, arches, and whorls for your class!

20. Ridge Characteristics
Minutiae—Are the ridge characteristics where the ridge structure changes or ends.
Scar

21. MINUTIA
BIFURCATION
(FORK)
RIDGE ENDING

22. MINUTIA
DOT
ENCLOSURE
(ISLAND)

23. 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?

24. Type of Fingerprints
Patent Prints
Plastic Prints
Latent Prints

25. Patent Prints
Patent prints occur when a substance such as blood, ink, paint, dirt, or grease on the fingers of the perpetrator of a crime leaves behind a readily visible print.
Essentially 2-D Imprint

26. Plastic Prints
Plastic prints have a three-dimensional quality and occur when the perpetrator indents a print into a soft substance such as wax, putty, caulk, soap, or…cold butter?

27. Latent Prints
Latent fingerprints are those that are “hidden” and are invisible to the naked eye.
These prints consist only of the natural secretions of human skin and require treatment to cause them to become visible.
Latent Print

28. Sweat Released through 2 glands in the skin: 99.0-99.5 % water
Eccrine Gland--largely water with both inorganic (ammonia, chlorides, metal ions, phosphates) and organic compounds (amino acids, lactic acids, urea, sugars)
Apocrine Gland--secrete cytoplasm and nuclear materials

29. Other Secretions Oily secretions:
Sebaceous Gland --secrete fatty or greasy substances.
Glands found in the hair follicle
Oils protects the hair and skin, and are present on the skin at all times.
The oily secretions are the major contributor to a latent print

30. Skin Layers

31. Lifting Latent Prints
Developing a print requires chemicals that react with secretions that cause the print to stand out against its background.
Powders--adhere to both sweat residue and oil deposits. Choose a color to contrast the background.

32. Fingerprint Powders
Gray and black powders – the most common, chosen to make the best contrast with the surface
Magnetic powder – applied with a special brush on leather and rough plastic surfaces.
Fluorescent powders – used to photograph latent prints on multi-colored surfaces. They fluoresce under ultraviolet light.

33. Things to consider when using fingerprint powders:
The brush should be dipped lightly into the container of powder and then the extra tapped off on the lid.
Only a very small amount of powder is needed to dust the print.
The brush should be held over the print and rotated between the thumb and fingers. The brush should be used to remove any extra powder.

34. Chemical Methods for Developing Latent Prints
Iodine-- fumes react with oils and fats to produce a temporary yellow brown reaction.
Ninhydrin-reacts with amino acids to produce a purple reaction on porous surfaces such as paper.
Silver nitrate--react with chlorides to form silver chloride, a material which turns gray when exposed to light. Method used as a last resort, as it destroys protein.
Cyanoacrylate--”super glue” fumes react with water and other fingerprint constituents to form a hard, whitish deposit which semi-permanently affix them to the surface.

35. Iodine Fingerprint

36. Ninhydrin Fingerprint

37. Silver Nitrate Fingerprint

38. Cyanoacrylate Fingerprints

39. Preservation of Developed Latent Prints
Always photograph
THEN
Collect the surface containing the print to preserve it in its entirety OR
Lift the prints with adhesive tape and place the tape with prints on a card with labels

40. Trends with Fingerprints
It is NOT possible to determine the age, sex or race of an individual solely from their fingerprints. However:
Manual labor tends to strengthen ridges.
Women tend to perspire at a lower rate than men.

41. Other Prints
Palm—friction ridges can be identified and may be used against suspects.

42. Other Prints
Footprints are taken at birth as a means of identification of infants.

43. Other Prints Lips—display several common patterns Short vertical lines
Short horizontal lines
Crosshatching
Branching grooves

44. Other Prints
The blood vessel patterns in the eye may be unique to individuals. They are used today for various security purposes.