Sarah Brake and Shannon Frederick
51st Great Idea
FINGERPRINTS
What are fingerprints? ….
An impression made by the papillary ridges on the ends of the fingers and thumbs. Fingerprints
are a means of identification; the ridge arrangement on every finger of every human is unique
and does not alter with age. Fingerprints serve to reveal an individual’s true identity thus making
it a means of identification that is crucial to law enforcement (Fingerprint, 2010).
There are three types of determined fingerprints:
Arch: the simplest and least common pattern; may be classified as either “plain” when the ridges
rise over the middle of the finger and “tented” when they rise to a point (Hendrix, 1989).
Loop: Has a triradius which is the point that three ridges from different directions meet at 120
degree angles, a core which is a ridge surrounded by fields of ridges that turn back 180 degrees
on themselves, and may be radial where the loop opens toward the thumb or ulnar where the loop
opens toward the little finger (Hendrix, 1989).
Whorl: has two triradii with the ridges creating different patterns inside (Hendrix, 1989).
Fingerprints are called latent prints because the impressions are generally invisible and need to
be developed further with a special powder or chemical; when they are less than a full
impression of all the ridges it is called a partial print (Osterburg, 2010).
The Henry Classification System
This system categorizes the ten-print fingerprint records into primary groupings based on
fingerprint pattern type, by classifying fingerprint records according to physiological
characteristics it reduces the effort used to search large numbers of fingerprint records (Henry
Classification System, 2003).
The System assigns each finger a number according to the order in which is it located in the hand
starting with the right thumb as number 1 and ending with the left pinky as number 10; it also
assigns a numerical value to fingers that contain a whorl pattern; fingers 1 and 2 each have a
value of 16, fingers 3 and 4 have a value of 8, and so on, with the final two fingers having a
value of 1 and fingers with an arch or loop pattern have a value of zero (Harling 1996).
L Pinky L Ring
Finger #
10
9
Value (if whorl)
1
1
L Middle L Index L Thumb R Thumb R Index R Middle R Ring R Pinky
8
7
6
1
2
3
4
5
2
2
4
16
16
8
8
4
The fingerprint record’s primary grouping is determined by calculating the ratio of one plus the
sum of the values of the whorl-patterned, even-numbered fingers; divided by one plus the sum of
the values of the whorl-patterned, odd-numbered fingers (Harling 1996).
This formula is represented below:
Henry Classification 1+ (Sum of whorled, EVEN finger value) = Primary Grouping Ratio
System Formula:
1+ (Sum of whorled, ODD finger value)
An example is an individual that has a fingerprint record with a ALWLALWAAL pattern series
the corresponding classification ratio would be 19:1. This is calculated below:
L Pinky L Ring L Middle L Index L Thumb R Thumb R Index R Middle R Ring R Pinky
Finger #
10
9
8
7
6
1
2
3
4
5
Value (if whorl)
1
1
2
2
4
16
16
8
8
4
Pattern Type
Arch
Loop Whorl Loop
Arch
Loop
Whorl
Arch
Arch Loop
Finger value
0
0
2
0
0
0
16
0
0
0
Example: 1+ (Sum of Even finger value) = 1+ (16 + 2) = 19
1+ (Sum of Odd finger value)
1 + (0)
1
Therefore, this individual belongs to the 19:1 primary group. If an individual does not have any
whorl-patterned fingerprints their classification ratio would be 1:1. If an individual has all ten
fingerprints containing a whorl pattern, his or her classification ratio would be 31:31. The Henry
Classification System allows for up to 1,024 primary groupings (Henry Classification System,
2003).
History
Fingerprints as a means of identification did not occur until the mid nineteenth century.
Fingerprint identification is known as dactyloscopy and is the process of comparing to ridge
impressions from human fingers, the palm of the hand, or even toes to see if those impressions
could come from the same person (Wikipedia, 2010).
The first case of identification arrest and conviction of a murder, based upon fingerprint
evidence was the Scheffer case of 1902. A man was identified as a thief and murderer who had
been previously arrested. There were fingerprints left on a showcase at the scene of the crime.
There have been many cases of people purposely mutilating their fingerprints in an effort
to avoid being identified from marks left on surfaces. Ways they have done this include burning
the finger tip, surgical alteration, and grinding off. An example was John Dilinger a man who
tried, and failed, burning his finger tips with acid.
Time Line
Prehistoric: In ancient Babylon Fingerprints were used on clay tablets for business transactions.
1686: Professor Malpighi discovered loops, ridges, and whorls.
1858: English first began using fingerprints for personal identification on business contracts.
1880: Dr. Faulds discovered the first fingerprint on a greasy alcohol bottle.
1882: Bertillon created the Bertillon system where inmates were classified by the measurements
of their body; fingerprints were not significant at this time.
1891: Vucetich began the first Fingerprint styles.
1900: Sir ER Henry wrote a book on fingerprint classification; thus emerged the Henry System
of Classification.
1905: U.S. Military began to use fingerprinting.
2005: INTERPOL’s Automated Fingerprint Identification System exceeds 50,000 sets of
fingerprints.
Conclusion:
Over the past 100 years fingerprinting has served all governments worldwide in identifying
criminals. There have never been two identical fingerprints in the many billion human and
automated computer comparisons. Fingerprinting is the most commonly gathered evidence and it
continues to be the best method for identifying people. In America we add tens of thousands of
people to the data base daily, and fingerprints solve ten times more unknown suspect cases then
DNA.