1. Fingerprints Dermatoglyphics and Dactyloscopy
SFS1. Students will recognize and classify various types of evidence in relation to the definition and scope of Forensic Science.
b. Distinguish and categorize physical and trace evidence (e.g. ballistics, drugs,
fibers, fingerprints, glass, hair, metal, lip prints, soil, and toxins).
SFS2. Students will use various scientific techniques to analyze physical and trace evidence.
a. Identify and utilize appropriate techniques used to lift and evaluate readable,
latent, plastic and visible fingerprints.

2. ESSENTIAL QUESTIONS
What are the basic principles underlying the forensic use of fingerprints?
How can you use minutiae to identify and distinguish prints?
How can you use patterns to identify and distinguish prints?

3. ESSENTIAL QUESTIONS
How can you identify and distinguish the three types of transfer prints?
What methods are used to detect and visualize specific types of prints?

4. History
The first systematic attempt at personal identification was devised in 1882 by a French police expert, Alphonse Bertillon.
The Bertillon system relied on a detailed description of the subject, combined with full length and profile photographs and a system of precise body measurements called anthropometry.

6. History
In 1892 Francis Galton published his classic textbook Finger Prints.
At Galton’s insistence, the British government adopted fingerprinting as a supplement to the Bertillon system.
The next step was the creation of classification systems capable of filing many thousands of prints in a logical and searchable sequence.
Sir Edward Henry devised a classification system between 1896 and 1925.

7. History
In 1903, when the Bertillon system could not distinguish between two men (Will West and William West), it was fingerprinting that clearly distinguished them.

8. What is a fingerprint?
Fingerprints are a reproduction of epidermal friction skin ridges found on the palm side of the fingers and thumbs, the palms, and soles of the feet.
During fetal development, friction ridges are formed and are permanent throughout life until death and decomposition.
These friction areas have a series of lines made up of hills (ridges) and valleys (furrows).
These are specialized for traction and enhanced sensory perception.

9. Fingerprint Principles
The basic principles underlying the use of fingerprints in criminal investigations are that:
(1) a fingerprint will remain unchanged during an individual’s lifetime;
(2) fingerprints have general ridge patterns that permit them to be systematically classified; and
(3) a fingerprint is an individual characteristic because no two fingers have yet been found to possess identical ridge characteristics.

10. Fingerprints are permanent
The epidermis is the outer layer of the skin, while the dermis is the inner layer of the skin.
The dermal papillae is the layer of cells between the epidermis and dermis, that is responsible for determining the form and pattern of the ridges on the surface of the skin.

12. Once the dermal papillae develop in the human fetus, the ridge patterns will remain unchanged throughout life except to enlarge during growth. Thus, a fingerprint will remain unchanged during an individual’s lifetime.

13. Injury can alter a fingerprint, but the damage must extend 1-2mm into the dermis.

14. Fingerprints have patterns
All fingerprints are divided into three classes on the basis of their general pattern: loops, arches, and whorls.
60% of people have loops
35% have whorls
5% have arches

16. Loops
A loop must have one or more ridges entering from one side of the print, recurving, and exiting from the same side.
All loops have one core
and one delta

17. Loops
If the loop opens toward the pinky, it is called an ulnar loop (94%).
If the loop opens toward the thumb, it is called a radial loop (6%).

18. Whorls
Whorls are divided into four groups: plain (71%), central pocket loop (13%), double loop (13%), and accidental (3%).
All whorl patterns have one or more cores and a minimum of two deltas.

19. Whorls
A plain whorl and a central pocket loop have at least one ridge that makes a complete circuit.
If a line drawn between the two deltas touches the spiral, then it is a plain whorl.
If the line does not touch the spiral, it is a central pocket loop whorl.

20. Whorls
The double loop is made up of two loops combined into one fingerprint.
An accidental either contains two or more patterns, or is a pattern not covered by the other categories.

21. Arches
Arches, the least common of the three general patterns, are divided into two distinct groups: plain arches (60%) and tented arches (40%).
Arches do not have type lines, deltas, or cores.

22. Arches
The plain arch is formed by ridges entering from one side of the print, rising and falling, and exiting on the opposite side (like a wave).
The tented arch is similar to the plain arch except that instead of rising smoothly at the center, there is a sharp upthrust, or spike, or the ridges meet at an angle that is less than 90 degrees.

23. Henry Classification System
Worldwide acceptance in 1899
Allows for up to 1,024 primary groupings
First, the fingers are assigned a value from 1-10
Next, a numerical value is assigned to fingers that contain a whorl pattern
Any fingers containing non-whorl patterns are assigned the number 0.

24. Henry Classification System
The fingerprint record’s primary grouping is determined by calculating a ratio:

25. Henry Classification System
If, for example, an individual has a fingerprint record with a LWAALALWLA pattern series (RT to LP), the corresponding classification ratio would be 19:1

26. Henry Classification System
Approximately 25 percent of the population falls into the 1/1 category; that is, all their fingers have either loops or arches.
A fingerprint classification system cannot in itself unequivocally identify an individual; it will merely provide the fingerprint examiner with a number of candidates, all of whom have an distinguishable set of prints in the system’s file.

27. Fingerprints are unique
The probability for the existence of two identical fingerprint patterns in the world’s population is extremely small (1:6,000,000,000)
Besides theoretical calculations, of the millions upon millions of individuals who have had their prints classified, no two fingerprints have been found to be identical.
The individuality of a fingerprint is not determined by its general shape or pattern, but by the careful study of its ridge characteristics, known as minutiae.

28. Minutiae
It is the identity, number, and relative location of these minutiae that imparts individuality to a fingerprint.
There are as many as 150 minutiae on the average finger, but typically only are identifiable.

33. Minutiae
After a three year study, it was determined that “no valid basis exists for requiring a predetermined minimum number of friction ridge characters which must be present in two impressions in order to establish positive identification.”
In a judicial proceeding, an expert must demonstrate a point-by-point comparison in order to prove the identity of an individual.

34. AFIS Automated Fingerprint Identification System
The heart of AFIS technology is the ability of a computer to scan and digitally encode fingerprints so that they can be subject to high-speed computer processing.
AFIS aids in classifying and retrieving fingerprints by converting the image of a fingerprint into digital minutiae that contain data showing ridges at their points of termination (ridge endings) and their branching into two ridges (bifurcations).
When the search is complete (a computer can make thousands of comparisons per second), the computer produces a list of file prints that must be examined by a trained fingerprint expert.

37. Visible Prints
Visible (patent) prints are made when fingers touch a surface after the ridges have been in contact with a colored material such as blood, paint, grease, or ink.

38. Latent Prints
Once the finger touches a surface, body perspiration, oils and/or proteins present on the finger ridges are transferred to that surface, leaving an impression.
Prints deposited in this manner are invisible to the eye and are commonly referred to as latent or invisible fingerprints.

40. Plastic Prints
Plastic prints are ridge impressions left on a soft material, such as putty, wax, soap, or dust.

41. Detecting Prints The best detection technique will depend on
The nature of the surface
The presence of contaminants
Environmental factors
Age of the prints
There are three categories of techniques that are used:
Instrumental/Optical
Physical
Chemical

42. Instrumental Detection
Instrumental detection should always be done first as they are non-destructive to the print.
These techniques are also useful in that they may significantly improve the results obtained by physical and chemical methods.

43. Instrumental Detection
RUVIS (Reflected Ultraviolet Imaging System)
Can image latent and processed prints by using intensified UV reflectance instead of fluorescence

45. Instrumental Detection
MXRF (Micro-X-ray Fluorescence)
Can image both visible and latent fingerprints by detecting the presence of of inorganic elements (Na, K, Cl) in print residue resulting from perspiration

47. Physical Detection
Latent prints deposited on smooth, hard and nonporous surfaces (e.g. glass, mirror, tile, and painted wood) are preferably developed by the application of a powder
Powders, available in a variety of colors, can be applied with a brush or magnetic wand, and adhere to perspiration and/or body oils of the print

50. Physical Detection
Latent prints deposited on rough, more flexible, nonporous surfaces (e.g. plastic, vinyl, aluminum foil, leather, tape) are preferably developed by cyanoacrylate (Super Glue ® ) fuming
Print development occurs when fumes from the glue adhere to the print, usually producing a white latent print

52. Physical Detection
Latent prints on porous surfaces (e.g. paper, cloth, raw wood) can be developed by iodine fuming
Heating iodine crystals produces vapors that combine with print oils to make them visible.
Iodine prints are not permanent and will fade, making it necessary to photograph the prints immediately.

54. Chemical Detection
Ninhydrin is used to develop latent prints on porous surfaces (primarily paper).
Reacts chemically with trace amounts of amino acids present in print residue to produce a purple-blue color
Prints can be “fixed” by spraying with a zinc chloride solution, changing the print to an orange-brown color
Can detect prints over 50 years old

56. Chemical Detection
DFO (1,8-diazafluoren-9-one) is similar to ninhydrin in that it is used for primarily paper, and it reacts with the amino acids in print residue
Fluoresces when illuminated with blue-green light (ninhydrin does not)
More sensitive and can develop up to 3x more prints than ninhydrin

58. Chemical Detection
Physical Developer is similar to other chemical methods in that it is used on porous surfaces
Reacts with lipids in print residue
It is a silver nitrate-based reagent used to develop prints when other chemical methods are ineffective
Can be used on wet samples

60. Sequence for Latent Print Development
Is the print on a porous or nonporous surface?
If nonporous…is surface smooth or rough? Can it be transported easily?
If smooth – use powders
If rough – use cyanoacrylate fuming
If easy to transport – use cyanoacrylate fuming
If porous…is surface wet or dry?
If wet – use Physical Developer
If dry – use iodine fuming  DFO  ninhydrin  PD

61. Transporting Prints
If the object is small enough to be transported without destroying the print, it should be preserved in its entirety
Prints on large immovable objects that have been developed with a powder can best be preserved by “lifting” with a broad adhesive tape
The tape is placed on a properly labeled card that provides a good background contrast with the powder