1. “Fingerprints cannot lie, but liars can make fingerprints” - proverb

2. In this chapter you will learn…
Why fingerprints are individual evidence
Why there may be no fingerprint evidence at the crime scene
How computers have assisted the process
To recognize general ridge patterns
Explain the difference between visible, latent, and plastic fingerprints
Develop latent prints using physical and chemical methods

3. Fingerprint Portfolio
3-ring folder
Keep/collect fingerprints recorded through various methods

4. Fingerprints Recording Prints – kept for comparison
rolling inked prints
primary identification number
FBI has national database called AFIS
Lifting Prints – retrieved from the scene
Black, white and fluorescent powder
Chemicals—ninhydrin, iodine, silver nitrate, cyanoacrylate
Other Types of Prints – can be individualized too!
Palm, lip, teeth, eye, ear, voice, shoe and footprints

5. 3 Principles of Fingerprints
1. A fingerprint is an individual characteristic
2. A fingerprint remains unchanged during an individual’s lifetime
3. Fingerprints have general ridge patterns that allow them to be systematically classified

6. Principle #1 Probability of 2 people with same prints is very small
Supported by theory & practice
FBI has nearly 50 million records
Individuality determined by study of Ridge characteristics known as minutiae
Average print contains 150 individual ridge characteristics
No basis for how many are needed to identify

7. Principle #2 Dermal Papillae Develop during 6th week
Helps provide firmer grasp and resistance to slippage
Fingerprints leave behind perspiration and oils, leaving a latent print
Dermal papillae – determines ridges
Dermal Papillae

8. Principle #2 Prints remain unchanged throughout life
Wounds must penetrate 1-2 mm beneath surface to scar prints (must reach dermal papillae)
John Dillinger – paid a doctor $5000 to dissolve his prints with corrosive acid – not successful

9. Principle #3 – 3 class division
Arch
Loop
Whorl 5%
65%
30%
Population Breakdown by %

10. Arch
Plain Arch
An arch has friction ridges that enter on one side of the finger and cross to the other side while rising upward in the middle. They do NOT have type lines, deltas, or cores.
Types
Plain
Tented
Exit here
Enter here

11. Arch
Plain Arch
Tented Arch
Arch not as high
Arch higher in center

12. Loop
A loop must have one or more ridges entering and exiting from the same side. Loops must have one delta.
Types
Radial—opens toward the thumb
Ulnar—opens toward the “pinky” (little finger)
Which type of loop is this, if it is on the right hand? Left hand?
Delta
Enter and exit from this side
These are the same except which way they open

13. Loop
Opens toward thumb
Opens toward pinky

14. Whorl Core Whorls have at least two deltas and a core.
A plain or central pocket whorl has at least one ridge that makes a complete circuit.
A double loop is made of two loops.
An accidental is a pattern not covered by other categories.
Types
Plain
Central Pocket
Double Loop
Accidental
Two Deltas

15. Whorl whorls have at least two deltas and a core.
A plain or central pocket whorl has at least one ridge that makes a complete circuit.
An accidental is a pattern not covered by other
categories.
A double loop is made of two loops.

16. Correctly Recording Prints
Refer to handout/video

17. Ridge Characteristics
Minutiae—characteristics of ridge patterns
Ridge ending
Short ridge
Dot or fragment
Bifurcation
Double bifurcation
Trifurcation
Bridge
Island
Enclosure
Spur

18. Fingerprint Minutiae

19. Primary Classification
The Henry—FBI Classification
Each finger is given a point value
right
left
Allows all fingerprints to be classified into only 1024 categories

20. Primary Classification
Assign the number of points for each finger that has a whorl and substitute into the equation:
right right left left left
index ring thumb middle little =
Left
right right right left left
thumb middle little index ring
That number is your primary classification number
Right

21. Primary Classification
Mr. Schatz’s Primary Classification is “goofball”
right right left left left
index ring thumb middle little 1
______ = 17
right right right left left
thumb middle little index ring 16
This is one of the 1024 categories…Who else in this room is in my category?

22. Automated Fingerprint Identification Systems
AFIS
Computer system for storing and retrieving fingerprints
Began in the early 1970’s to:
Search large files for a set of prints taken from an individual
Compare a single print, usually a latent print developed from a crime scene
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 (1999)

23. AFIS

24. Types of Prints
Plastic prints – indented or molded prints – made from pressing a finger into a plastic-like material to form a negative impression.
Visible prints – left by a finger that has touched a colored surface such as blood, paint, ink, grease, mud or dust.
Latent prints – invisible prints that must be developed by chemical or physical means.

25. Invisible prints that must be developed by chemical or physical means.
Latent Prints
Invisible prints that must be developed by chemical or physical means.
Use a dusting powder or chemical means to develop the print
Take pictures of print
Lift the print when possible
If you can’t lift the print…Recover the whole item the print is on and send to lab

26. Latent Prints
The reason you get these prints is because you secrete different substances from your skin.
Most secretions come from three glands:
Eccrine (Sweat)—largely water, salts and amino acids (protein)
Apocrine—secrete pheromones and other organic materials.
Sebaceous—secrete fatty or greasy substances.

27. Developing Latent Prints
Powders—adhere to both water and fatty deposits. Choose a color to contrast the background.
Iodine—fumes react with oils and fats to produce a temporary yellow brown reaction.
Ninhydrin—reacts with amino acids to produce a purple color.
Silver nitrate—reacts with chloride to form silver chloride, a material which turns gray when exposed to light.
Cyanoacrylate—“super glue” fumes react with water and other fingerprint constituents to form a hard, whitish deposit.

28. Partial Prints
You do not need to lift a complete fingerprint to have sufficient ridge detail (minutia) present for an identification.

29. Documenting Prints Lift the print and put it on an index card
Case Number
Victim Information
Incident Location
Incident Date
Recovering Officer Name
Object or Location of Recovered Lift
Method of Development
Orientation if Needed
Diagram where you found it
Put all pertinent information on the card

30. Documenting Prints

31. Cyanoacrylate Fingerprints

32. Cyanoacrylate Chemistry
Most super glue’s contain the chemical necessary to attach to the fingerprint remains
Necessities:
The container must be as airtight as possible
A small heater is necessary to vaporize (boil) the Cyanoacrylate
Water in the air helps the reaction to complete

33. More info…
The boiling point of cyanoacrylate is thought to be somewhere between 120 – 150 degrees F
The reaction can take time
If left too long, results become poor

34. Ways to speed reaction time…
Fume Circulation
By using a fan and constantly circulating the air inside the chamber, the reaction becomes more efficient
Chemical Acceleration
Replace heat with sodium hydroxide added to super glue
Water Vapor Method
Introduce more water into the air
Can be as simple as leaving container of water in the chamber

35. Fingerprint Test Fingerprint notes Classification system (given #’s)
3 principles of fingerprinting
characterization
Classification system (given #’s)
Performance --- latent development

36. Chemical Development Iodine Fuming Ninhydrin Silver Nitrate
Sublimation
Does not last unless “fixed”
Ninhydrin
Useful for porous surfaces (paper)
Silver Nitrate
Reacts with salt
Good for very old prints
Must be done last

37. Silver Nitrate Development
Mix (with popsicle stick) .85g of Silver Nitrate w/ 50ml distilled water
Fingerprint a small part of an index card
Drop card in and let sit for 5 minutes
Remove and put in black light hood

38. Other Prints Ears—shape, length and width
Voice—electronic pulses measured on a spectrograph
Foot—size of foot and toes; friction ridges on the foot
Shoes—can be compared and identified by type of shoe, brand, size, year of purchase, and wear pattern.

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

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

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

42. Other Prints
Teeth—bite marks are unique and can be used to identify suspects. These imprints were placed in gum and could be matched to crime scene evidence.

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