1. Chapter 14 Forensic Science
FINGERPRINTS
Chapter 14
Forensic Science

2. History of Fingerprinting
Bertillon (1883) First system for identification
Galton (1892) Published first textbook: Finger Prints
Henry (1897) Fingerprint system adopted by Scotland Yard
NY City Civil Service Commission (1901) used to certify all applications
FBI (1924) combined prison records from Leavenworth with their records to form the first national fingerprint “database”.

3. Three Fundamental Principles
Fingerprints show individual characteristics
Fingerprints do not change over a lifetime
Fingerprints have ridge patterns that can be easily classified

4. 1st Principle: No two fingerprints look alike
Classified by ridge patterns or minutiae
Ridge patterns must match in both characteristics and location on the finger
No national standard but 8-16 ridge patterns are needed between a unknown and known fingerprint for there to be a match

5. 2nd Principle: Fingerprints stay the same over a lifetime
Friction ridges found on lips, fingers and palms of hands and soles of feet
Outer layer of skin - epidermis
Inner layer - dermis
Junction between the two layers is - dermal papillae
John Dillinger tried to obliterate his finger prints by making deep cuts and pouring sulfuric acid into the cuts. Within a few years the same friction ridge patterns returned with some scaring. Post Mortem fingerprints taken by the FBI confirmed that his prints were unchanged.

6. 2nd Principle Raised lines or hills - Ridges
The valleys between the hills - Grooves
Pores in between the ridges are openings for sweat glands
Sweat and oils leave an impression on the surface - latent print

7. 3rd Principle: Classified Ridge Patterns
Three Ridge Classes:
LOOPS - 60 to 65%
WHORLS - 30 to 35%
ARCHES - 5%
Percentage of the patterns found on the epidermis in the general population

8. Classification

9. LOOPS In order to distinguish between ulnar and radial loops you must:
1) know from which hand the loop pattern comes from 2) place your hand palm side down over top of the impression and determine if the recurving ridges originate from the little finger side or the thumb side.
3) If the ridges flow in from the little finger side this would be an 'ulnar' loop.
4) If the ridges flow in from the thumb side this would be a 'radial' loop.

10. WHORLS All whorls have at least two deltas.
A plain whorl has at least one ridge that makes a complete circle
The ridge can be in the shape of a spiral or an oval.

11. ARCHES
The Arch pattern is made up of ridges lying one above the other in a general arching formation.
The tented arch pattern consists of at least one upthrusting ridge, which tends to bisect superior ridges at right angles, more or less.

12. Basics
The individuality of a fingerprint is determined by a careful study of ridge characteristics
All fingerprints are divided into one of the three general patterns: loops whorls or arches.
Latent (invisible) fingerprints are produced when you touch a smooth surface and transfer an impression of your finger with sweat and oils

13. The Henry System Both hands could be expressed as a fraction.
Problem was the system was designed for only about 100,000 sets of prints.
The number of people exceeded the system very quickly.
In 1901 – the original classification system used for fingerprints was developed by a man named Henry.
He converted all 10 fingers into a series of letters and numbers.

14. FBI System
This system provides the examiner with a more limited pool of candidates from which to examine for matches.
By adding extensions and expanding the original Henry System, the FBI was able to create a limitless system for comparing fingerprints.

15. Henry System Basics System is based on the presence of whorls
Whorls on first pair is 16 on second – 8, third pair -4, fourth – 2 and last pair value of 1
Any finger that has an arch or loop is assigned a 0.
After all the fractions are added a value of 1/1 is added to the total for the final fraction
R Index R Ring L Thumb L Middle L Little
R thumb R Middle R Little L Index L Ring
= 17

16. Integrated Automated Fingerprint Identifcation System (IAFIS)
Ability of the computer to scan and digitally encode fingerprints
The encoding allows minutiae to be rapidly scanned
Can screen a set of 10 prints against a file of 500,000 sets of 10 prints in .08 seconds
Ridge endings (terminations)
Branching of ridges (bifurcations)
Screen out imperfections in latent prints
Can send prints immediately to FBI database

17. DETECTING FINGERPRINTS
Locating fingerprints
Visible and plastic are easy to find but latent is more difficult
Different surfaces require different visualizing methods
Hard non-porous surfaces (glass, tile, painted wood) require visualizing powders or Super glue
Three kinds of crime scene prints:
Visible – can be seen without technology
Latent – not visible without some technology
Plastic – impressions made in soft materials such as soap, wax or putty

18. DETECTING FINGERPRINTS
Soft and porous surfaces (cloth, paper, cardboard) require chemical treatment
Can use RUVIS (Reflected Ultraviolet Imaging System) which locates prints on soft surfaces without the use of chemicals with UV light

19. DEVELOPING LATENT PRINTS
POWDERS:
Adhere to perspiration and body oils
Almost any color – grey and black being most common
Grey – aluminum dust
Black –carbon or charcol
Magnetic – charged
Fluorescent – glow under UV light
FUMING:
Iodine – iodine sublimates when heated giving off fumes.
The fumes adhere to the latent print
Old technology – does not last long print visible fades in minutes

20. DEVELOPING PRINTS NINHYDRIN
The chemical reacts with amino acids to produce a purple-blue color
Usually used as an 0.6 % solution sprayed as an aerosol on porous surfaces
Takes 1 to 48 hours can increase developing by heating in an oven
Effective on paper that was 15 years old
FUMING:
Super glue (Crazy glue) can visualize a print on non-porous surfaces as well as metals, tape, leather and plastic bags
Heating the Super glue releases cyanoacrylate ester fumes
Fumes produce a white fluffy print

21. DEVELOPING PRINTS PHYSICAL DEVELOPER
Chemical mixture – silver nitrate based
Works even if item was wet –then dried.
Used as the “last resort” because washes away all traces of proteins
NEWEST TECHNOLOGY
Laser light can detect latent
prints that fluoresce with certain components of sweat.
Alternate light sources:
High-intensity quartz halogen
Xenon-arc
LED’s (light emitting diodes)
DFO (1,8-diazafluoren9-one)
Chemical works with alternate light sources

22. PRESERVING DEVELOPED PRINTS
If the object the print is on is small – the entire object should be taken to the laboratory
If the object is too large - then the developed print must be “lifted”.
Can use special clear tape to lift a print developed with a powder
Tape with print is placed on a card with good background contrast
Once a print is developed it must be preserved as evidence
STEP ONE: photograph developed print
STEP TWO is determined by the size of the object the print is on

23. DIGITAL IMAGING
Digital imaging converts a fingerprint image into pixels
Can be done with a scanner or digital camera
Lifted fingerprints are not usually in perfect condition – making analysis even more difficult
Digital imaging programs can now enhance the lifted/partial prints to make identification more accurate