A detailed presentation about fingerprints.

1. What Fingerprints Are
• Fingerprints are patterns of friction ridge
skin
• Fingers and palms of hands, soles of feet
and are characterized by ridges (hills) and
valleys (furrows)
• Patterns form on skin surfaces early in
embryonic development and are carried
through life

3. Fingerprint Patterns
• There are three basic patterns of fingerprints:
• Arches – can be plain or tented
• Loops – radial or ulnar, depending on whether
direction of slope of pattern is towards inner arm
bone (radius) or outer arm bone (ulna)
• Whorls - most complex, and contain central
pocket, double loop, and accidental

7. Henry System
• Parts of the Henry System are:
–Key
–Major
–Primary
–Secondary
–Subsecondary
–Second Sub Secondary
–Final

10. Computer Based Fingerprint Files
• Automated Fingerprint Identification
Systems (AFIS) are used by law
enforcement
• This system searches databases for 10
point set of prints and searching large files
for single prints retrieved from a crime
scene

11. Law Enforcement Information
Systems
• FBI recently made its criminal database of
known fingerprint cards (IAFIS) available
• Latent print examiners can search
unknown latent impressions to assist in
identification of suspects or victims

12. Types of Evidentiary Fingerprints
• Three types of fingerprints
encountered at crime scenes or
on evidence:
–Patent
–Plastic
–Latent

13. Types of Evidentiary Fingerprints
• Patent – clearly recognizable fingerprint that
needs no processing – could be in grease,
blood, dirt, or oil
• Plastic print – also called an impression or
indentation print- could be in tar, butter, silly
putty
• Latent print – requires additional processing to
be rendered suitable for comparison –
processing is called development or
enhancement

14. Development of Latent Prints
• Fingerprint residue, which is composed of
inorganic and organic residues, comes
from eccrine glands and from touching
areas where apocrine glands in body are
before touching item
• Fingerprints can also come from touching
external sources- oils, tars, etc and then
touching surface of object

15. Physical Methods
• Latent fingerprint powder dusting is primary
method of visualizing fingerprints
• Black fingerprint powders generally have best
results
• Magnetic powders and brushes are now
available
• Small particle reagent (SPR) is sprayed on print
and adheres to lipids from prints

17. Chemical Methods
• Chemical methods of techniques for
visualizing fingerprints are:
–Silver nitrate – rarely used anymore
–Iodine fuming – very common –dirty
brown colored print and needs to
photographed quickly as it fades

18. Ambient Light

19. Silver Nitrate

20. Iodine-fumed

21. Chemical Methods
–Ninhydrin – used since 1910 and is slow
to react unless heat and humidity are
present – develops bluish-purple prints
–Cyanoracrylate (superglue) is used to
fume and yields an off white colored
print – use of heat and humidity
accelerates process

22. Ninhydrin

23. Cyanoacrylate
ester

24. Chemical Methods
• Physical Developer (PD) photographic
type process based on deposition of silver
onto latent fingerprint residue
• US Secret Service modified procedure and
uses colloidal gold to enhance prints
• Normally used after ninhydrin

25. Super glue
developed under
UV illumination
Treated
with ardrox
dye

26. Super glue
developed under
UV illumination
Treated with
Rhodamine-
6G

27. Combination and Special Lighting
• Various types of lights are used to
illuminate fingerprints
• Bright white light (525 nanometers),
lasers, and black lights with the use of
fluorescent powders are commonly used

28. Alternative
light source

29. Bloody Fingerprints and Other
Special Situations
• Bloody fingerprints normally are not latent
– primarily composed of blood
• Most processes for latent print chemical
enhancement do not interfere with blood
collection for DNA profiling by PCR for
CODIS
• Many bloody fingerprints are enhanced by
peroxidase- reaction chemicals

31. Bloody Fingerprints and Other
Special Situations
• Fingerprints that are on tape, especially
the sticky side, were developed by crystal
violet
• Most common method today is sticky side
powder, which is composed of lycopodium
(plant pollen) that is mixed with detergent
and water.

32. Recognition, Collection and
Preservation of Fingerprint
Evidence
• Fingerprints are among best evidence
• Objects at a crime scene which are believed to
contain prints should be collected
• If collection is impossible, latent development
techniques should be used
• Photographing of developed prints is advisable

33. Fingerprint Identification- The Heart
of the Matter
• David Ashbaugh (1999) noted fingerprint
individuality:
– Friction ridges develop in fetuses
– Friction ridges remain unchanged except for
scars
– Friction ridge patterns and details are unique
– Ridge patterns vary within certain boundaries
that allow patterns to be classified

34. Fingerprint Identification- The Heart
of the Matter
• Overall process of fingerprint examiner
according to Ashbaugh, A.C.E.V. :
–Analysis
–Comparison
–Evaluation
–Verification