FINGERPRINTS GUIDED NOTES
Name: ____________________________________
What are fingerprints?
 Does everyone have a unique fingerprint?
 How, why, and when do fingerprints develop?
 Can you alter your fingerprints?
History of Fingerprinting
Fingerprints have served as unique signatures since prehistoric times
 Early potters & scribes left fingerprints in clay
 Businessmen in ______________________________________ (8th century AD) used fingerprints on business
contracts
Scientific study of fingerprints
 1891 ______________________________________
 classified fingerprints using loops, whirls, and arches
 demonstrated that fingerprints are unique and unchanging
 1892 First reported use of fingerprints to solve a crime, in Argentina.
 1899 Sir Edward _____________________ developed a way of classifying fingerprints so that investigators could
quickly narrow down possible matches.
“Henry system” of classification
Used until computer systems developed
 1910 Thomas Jennings is first person in US convicted based on fingerprint evidence
AFIS
 Automated Fingerprint Identification System
 Used since 1960s
 Scans, encodes, and searches fingerprint images
 After match(es) found, a fingerprint expert evaluates the matches
 Problem with current system: not all databases linked
Fingerprint Patterns
 What ARE fingerprints?
 The fingers, toes, palms of hands, and soles of feet have friction ridge skin made of ridges (raised areas)
and furrows (valleys).
Are ridge light or dark? Why?
Arches
 Arches ________________________________________________________________________
______________________________________________________________________________
 Least common pattern (~5%)
 Can be ________________ (low rise) or ______________________ (high rise)
Loops
 Loops _______________________________________________________________
____________________________________________________________________
 Most common pattern (~65%)
 Have a _____________________ (the center of the pattern) and a ___________________ (a triangular area)
 Radial loops open towards the radius of the arm (i.e. towards the thumb).
 Ulnar loops open towards the ulna of the arm (i.e. towards the pinky)
Whorls
 Whorls look like “whirlpools”
 Have a core and two or more deltas
 _________________________________ are spirals or concentric circles
 ________________________________ whorls look like a loop with a whirl in the middle
 ________________________________ have two loops that collide to make an “S” shape
 ________________________________ are irregular
Types of Fingerprints
•
____________________________________ - prints that can be seen by the naked eye, made if the finger has
touched grease, blood, paint, etc.
•
_____________________________________ – prints that are invisible to the naked eye; formed from natural
body oil and perspiration
•
_____________________________________ – 3D negative impression of a fingerprint, made by pressing a
finger into a soft, moldable material, such as putty, wax, glue, candy, etc.
Collecting Fingerprints for Evidence
•
________________ and ________________ prints can often just be photographed for evidence.
•
____________________________________ must be made visible to be observed & collected.
Visualizing Latent Prints
1) _________________________________________
•
Most prints (even so-called latent prints) are at least partially visible and can be found by shining a
_____________________ or _________________________ source along surfaces
_______________________.
•
Used to find prints, especially over large areas
•
UV lights and lasers make fingerprints _______________________, and will reveal more prints than
regular flashlights
•
After finding prints with oblique lighting, the prints will need to be further developed (by the methods
described next) so that a permanent record can be made)
2) ________________________________________
•
Can be used to locate (over small areas), enhance, and preserve prints
•
Powder is lightly dusted onto a surface so as not to smear the prints.
•
The powder is ____________________ with ____________________ and put onto
____________________________________.
•
Powders come in a variety of colors, and some are magnetic
3) ________________________________________
More effective than dusting on porous surfaces, such as paper, leather, styrofoam, etc
A. ______________________________________
•
Used on ______________ surfaces, including _________________
•
Object is dipped in or sprayed with ninhydrin solution
•
Reacts with amino acids in print
•
Turns purple
B. _____________________________________
•
Used on _________________ because it is impermanent
•
Evidence is placed in fuming chamber with crystal iodine
•
Iodine is trapped in oils of print to produce brown color
•
Will fade over time
C. __________________________________________
•
Evidence is placed in a fuming chamber with superglue
•
Heat accelerates the process
•
The glue bonds to the print, forming a ___________, _________________,
__________________________________.
•
Superglued prints are usually further treated with chemicals or powders to enhance the visibility of
the print.