Fingerprints
CHAPTER 14
History of Fingerprinting
 First used by Chinese to sign documents (3000 yrs. Ago
 Henry Fauld first published paper describing use of
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fingerprints for identification ; 1880 suggested these
ridges could be used to identify criminals
Francis Galton—published book about fingerprinting in
1892 that led increase in use of fingerprinting
Sir Richard Henry—came up with classification system
for fingerprints
Began in US in 1901 in New York City
1924—FBI started fingerprint records for matching
suspects
Introduction of Fingerprints—Fundamental
Principle 1
 Fingerprints are one of a
kind entities
 Fingerprint individuality
occurs in the ridge
characteristics or
minutiae
 The minutiae are ridge
endings, bifurcations,
enclosures, and other
details
Fingerprint Ridge Characteristics—Makes 100%
original
 Bifurcation—indentation
 Ridge Ending—End of
line
 Ridge—Upraised line
 Enclosure—line closes off
a space
 Ridge Island—small dot
Fingerprints: Fundamental Principle 2
 They are unchanged
during one’s lifetime
 Also found on palms and
soles of feet; designed to
give some friction to
avoid slippage from
surfaces
 Oils and sweat prints
make invisible latent
prints on surfaces
Fingerprints: Fundamental Principle 3
 Have common patterns that
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allow for classification
Loop—ridge lines that enter from
one side of the pattern and exit at
same side
Whorl—ridge patterns that are
rounded or circular and have two
deltas; plain whorl, central
pocket loop, double loop, and
accidental
Arch—ridge lines enter pattern
from one side and exit from the
other; plain and tented
http://www.youtube.com/watch?
v=Ry8920R7bxs&feature=relate
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Fingerprint Classification
 First level—assigns a fraction
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number
Presence of absence of whorl
pattern gives determination
If a whorl is present on pair
#1, 16 on pair #2, 8, on pair
#3, 4, on pair #4, 2 and on
pair #1 1
Zeros are put in when there
aren’t any whorls in pairs
Pair 1 is Right index/Right
Thumb, Pair 2 is R Ring/R
Middle, Pair 3 is L Thumb, R
Little, Pair 4 is L Middle/L
Index, Pair 5 is L Little/L
Ring
Automated FingerPrint ID system (AFIS)
 Print ridge are now matched
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to prints in system
Livescan takes inkless digital
prints and compares them to
AFIS database
Speedy and accurate
AFIS gives list of potential
prints and then a trained
analyst will make decision if
prints match the tested ones
http://www.youtube.com/wat
ch?v=ZKi1CKTRCQM&featur
e=related
Fingerprints
 Visible print—left in dink,
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dirt, blood, something visible
Plastic print—impression in
soft surface like dirt, clay, etc.
Latent prints—invisible due to
oil and sweat deposits on
surface
Visible and plastic prints are
easily detected
Latent prints are not as easily
detected
Reflected Ultraviolet Imaging
System (RUVIS) use
ultraviolet imagery to locate
latent prints
Developing Latent Prints--Powders
 Fingerprint powders—
applied with camel hair
brush and adhere to oils
and perspiration; usually
gray and black and selected
to contrast background
color
 Magnetic sensitive
powders—uses magnetic
brush to dust prints; no
contact damage
 Fluorescent powdersfluoresce under UV light
Developing Prints—Iodine and Ninhydrin
 Iodine fuming—visualize
prints by exposing to iodine
 Iodine sublimes to gas
from solid and make print
visible
 Ninhydrin—chemical used
to develop latent prints on
porous materials by
reacting with amino acids
in sweat; mixed with
solvent like acetone or
ethyl alcohol and sprayed
on surface; can take 1 to 48
hours
Other methods for developing Prints
 Physical developer—silver
nitrate reagent used to
develop latent prints on
porous surfaces
 Super glue fuming—exposes
latent prints on nonporous
surfaces to cyanoacrylate
vapors; named for super glue;
can be done on site
 Laser light—perspiration
fluoresces with laser light
 http://www.youtube.com/wat
ch?v=NjGyil6k75M&feature=f
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Preservation of Prints
 After analysis, prints must be
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preserved for the courts
Photographs of print and
location of print at crime scene
Take entire item with print as
evidence (if small enough)
From large immovable objects,
prints must be lifted by adhesive
tape (like scotch tape)
Digital imaging—prints are
converted to digital image and
can be enhanced for the most
accurate analysis
Digital images can be put into
print database
Allows analysis of just portion of
print