1. FINGERPRINTS

2. A HISTORY OF FINGERPRINTS
A classification system for fingerprints was developed in 1891.
Francis Galton published his book "Finger Prints" in 1892 which included the following principles.
* There are 3 types of  fingerprint patterns
* Prints do not change over time
* Prints are unique to the
individual. Not even
identical twins – who
have identical genes
have the same prints!
Alicia Brown MAI Making Links Forensics, September 2006

3. HOW ARE FINGERPRINTS MADE?
Definition of a "print“: When oil from the body
mixes with sweat and dirt and you touch something, these
adhere to the surface of the object, leaving a print.
Fingerprint identification (Dactyloscopy) is the process of comparing questioned and known prints to determine if the impressions are from the same finger (or palm, toe, etc.).
Fingerprints are a very useful resource at a crime scene.  Fingerprints are left everywhere at anytime. 
Many cases have been solved with the use of fingerprints. 
Alicia Brown MAI Making Links Forensics, September 2006

4. HOW PRINTS ARE USED IN A CRIMINAL INVESTIGATION?
Each time the FBI books a suspect in a crime they make inked fingerprints of the person to be kept on file.
About 200 million prints are on file.
Computer software can run a set of prints through scanning devices and a match can be found in  minutes.
There are at least 150 different ridge characteristics on the average fingerprint. If specific points of reference for any two fingerprints identically compare, a match is assumed.
In a judicial case, 12 points must match in order to prove the identity of a specific person.
Alicia Brown MAI Making Links Forensics, September 2006

5. Alicia Brown MAI Making Links Forensics, September 2006
TYPES OF PRINTS
Human fingerprint patterns fall into three main groups:
Arches
Loops
Whorls
Despite these broad patterns, each individual has a unique set of fingerprints, which can be used as a means of personal identification.
Alicia Brown MAI Making Links Forensics, September 2006

6. Alicia Brown MAI Making Links Forensics, September 2006
ARCHES
Account for 10 percent of fingerprint. They have lines
that start at one side of the print and then move
toward the centre of the print and leave of the other
side of the print. Arches have no type lines or deltas.
Plain Arch - simplest of all the
fingerprint patterns.
Tented Arch - ridges rise in a
sharp thrust or spike in the
centre of the print. at an angle
less than 90 degrees
Alicia Brown MAI Making Links Forensics, September 2006

7. Alicia Brown MAI Making Links Forensics, September 2006
WHORLS
Whorls account for 30 percent of fingerprints. Whorl
patterns have a lot of circles that do not exit on either
side of the print. All whorls have at least 2 deltas.
Plain Whorl - A line drawn between
the 2 deltas touches one of the
spiral ridges.
Central Pocket Whorl - An imaginary
line drawn between the 2 deltas
does not touch the spiral ridge.
Alicia Brown MAI Making Links Forensics, September 2006

8. Alicia Brown MAI Making Links Forensics, September 2006
LOOPS
Loops are the most common type, accounting for about
60 percent of all fingerprints. They have lines that start
at one side of the print, and then move toward the
centre of the print and leave on
the same side of the print they
started on.
Left Loop - loop opens toward the
little finger (ulna)
Right Loop - loop opens toward the
thumb (radius)
Double Loop - any 2 loops combined
into one print
Mixed figure - contains 2 or more
patterns (not including a plain
arch) or the pattern is not covered
by other categories.
Alicia Brown MAI Making Links Forensics, September 2006

9. FINER DETAILS – WAYS TO DISTINGUISH PRINTS
TYPE LINES are the line before the pattern changes. The
two diverging ridges usually coming into and splitting
around an obstruction, such as a loop.
A DELTA is the ridge point nearest the type line
divergence. It usually forms a triangle.
The CORE is the
approximate centre
of the pattern.
Examples of these
characteristics are
shown :
Alicia Brown MAI Making Links Forensics, September 2006

10. Types of fingerprints left at crime scenes
Visible prints - can be seen with the naked eye
Latent prints - are invisible
Plastic prints - leave an impression on objects such as soap or wax
Alicia Brown MAI Making Links Forensics, September 2006

11. Methods used to obtain fingerprints
There are many methods of obtaining latent prints:
Dusting
Carbon powder for white/light coloured surfaces
* Lanconide powder for black * Aluminum powder for hard or dark coloured
surfaces or mirrors and metal surface
Fuming
* use of super glue (Cyanoacrylate)
* iodine
* ninhydrin
* silver nitrate
* Gentian violet
Laser technology
Alicia Brown MAI Making Links Forensics, September 2006

12. Alicia Brown MAI Making Links Forensics, September 2006
Now it’s YOUR TURN!
Let’s have a go at taking our own fingerprints and then trying to classify them. Use your hand-out to assist.
Later, we will use this knowledge to lift a print from the crime scene, classify it and then match it to one of the suspects
Alicia Brown MAI Making Links Forensics, September 2006