Dermatoglyphics

1. Dermatoglyphics Introduction to Fingerprint Identification

2. How Fingerprints Are Formed Fingerprints form in the basal layer of our skin with the epidermis over it in order to protect it. Prints similar to our fingerprints are formed on our palms, soles of our feet, and our lips.

3. Fingerprints • A fingerprint is an INDIVIDUAL CHARACTERISTIC • no two are alike and no two have yet been found to possess identical ridge characteristics. • Fingerprints are the product of your genes as well as the environment of the womb during development in the first trimester (nutrition, blood pressure, contact with the womb) • Once developed, fingerprints do not change over the course of your life, although they may be altered or scarred • They evolved in some primates and other animals (e.g. koalas) for firmer grasp and resistance to slippage • They are comprised of a series of lines corresponding to hills (ridges) and valleys (grooves).

4. Efforts to Remove Fingerprints are Unsuccessful • John Dillinger’s Prints Before and After Treatment with Acid

5. Latent Prints • Each skin ridge is populated with a single row of pores—openings for ducts leading from sweat glands • These ducts secrete a combination of mainly water, oils, and salts. Dirt from everyday activities also mixes in. • Oil in fingerprints comes from the hand contacting other parts of the body (e.g. face) or other substances containing oil • Perspiration from eccrine glands discharges and deposits water (≈95%), urea, salts and proteins on surface of skin. • When the finger comes into contact with another surface, the water and dissolved substances are transferred • This leaves an impression of the finger’s ridge pattern (fingerprint) • These are typically invisible to the eye and referred to as latent fingerprints

6. Characteristics of Prints and Minutiae Characteristics are named for their general visual appearance and patterns

7. Types of Prints

8. Types of Prints Divided into three classes (each class is then subdivided): • LOOP 60-65% OF THE POPULATION HAS LOOPS • WHORL 30-35% WHORLS • ARCH AND 5% ARCHES

9. Loops • A loop must have one or more ridges entering from one side of the print, recurring and exiting from the same side. • If loop opens toward little finger= ulnar loop • Opens in the direction of the thumb= radial loop • ALL LOOPS HAVE ONE DELTA

10. Whorls • All whorl patterns must have type lines and a minimum of two deltas. • A PLAIN WHORL and CENTRAL POCKET LOOP have at least one ridge that makes a complete circuit. This ridge may be in the form of a spiral, an oval, or any variant of a circular form. • The main difference between these two patterns can be shown if an imaginary line is drawn between the two deltas contained within the two patterns. • If the line touches any one of the spiral ridges, the pattern is determined to be a plain whorl, if no ridge is touched, the pattern is a central pocket loop.

11. Arches • Of the two types of arches, the PLAIN ARCH is the simplest of all fingerprint patterns. It is formed by ridges entering from one side of the print and exiting on the opposite side. These ridges tend to rise at the center of the pattern, forming a wavelike structure. • The TENTED ARCH is similar, but instead of rising smoothly at the center, there is either a sharp up thrust or spike, or the ridges meet at an angle that is less than 90 degrees.

12. Double Loops and Accidental • The DOUBLE LOOP is made up of any two loops combined into one fingerprint. • Any print classified as ACCIDENTAL either contains two or more patterns (not including the plain arch) or the pattern is not covered by other categories i.e., a combination loop and a plain whorl or a loop and tented arch.

13. Dermatoglyphics • Individuality is not determined by general shape or pattern but by a careful study of its ridge characteristics • (also called minutiae) • Identity- number- and relative location of features that impart individuality. • The features should be in the same relative location to one another. • In court, a point-by-point comparison must be made to establish identity http://cnx.riceedu/content/m12574/latest/match.jpg

14. Minutiae (see pg. 139 in Bertino)

15. Making Comparisons • There are as many as 150 individual ridge characteristics on the average fingerprint. • a vast majority of prints recovered from crime scenes are partial impressions- showing only a segment of the print. • Expert has to compare a small number of ridge characteristics from the recovered print to the known recorded print. • Criteria of individuality in court generally requires 8-16 matching characteristics, but often this number is not as important as the expertise of the fingerprint examiner

16. Matching Minutiae

17. Types of Fingerprints • Patent prints: visible prints left on smooth surfaces when blood, ink, or some other liquid comes into contact with the hands and is then transferred to another surface. • Plastic prints: an actual indentation left in some soft material i.e. clay, putty, wax. • Latent prints: hidden prints caused by the transfer of oils or other body secretion onto a surface.

18. Databases Suspects (or criminals at booking) are printed on a TEN CARD which rolls each of their fingers in ink and then onto a card in a standard format

19. IAFIS • INTEGRATED AUTOMATED FINGERPRINT IDENTIFICATION SYSTEM • Large database of fingerprint collections- using individual characteristics of fingerprints converted into DIGITAL MINUTIAE: ridge endings, and branching. • Location and relationship of minutiae in a digitally recorded geometric pattern • A computer can make thousands of fingerprint comparisons in a second. • IAFIS does not make final verification of print identity, but rather flags prints with the closest correlation to the search prints. • ALLOWS CRIMINAL INVESTIGATORS TO SPEND LESS TIME DEVELOPING SUSPECT LISTS AND MORE TIME INVESTIGATING SUSPECTS GENERATED BY THE COMPUTER. • Fingerprints are voluntarily submitted to the FBI by local, state, and federal law enforcement agencies. These agencies acquire the fingerprints through criminal arrests or from non-criminal sources, such as employment background checks. The FBI then catalogs the fingerprints along with any criminal history linked with the subject.

20. Methods of Detection

21. METHODS OF DETECTING LATENT FINGERPRINTS • THE METHOD OF CHOICE WILL DEPEND ON THE SURFACE BEING LIFTED OR TESTED. • Hard and non-absorbent surfaces (glass, mirror, tile, and painted wood) require different approaches than soft and porous- paper, cloth, or cardboard. • The most challenging thing an examiner faces is location of latent prints.

22. On hard surfaces: Powder Grey or black Florescent Magnetic Superglue Lighting Techniques (fluorescence and UV) Visualization of Latent Prints • On soft surfaces: • Iodine fuming • Nonpermanent visualization • Ninhydrin • Reacts with proteins • Gentian violet • Binds to cells and oils on tape Ninhydrin

23. Ultraviolet Imaging Systems • Light sources can be used to locate prints which can then be enhanced and lifted using other methods. This saves time and energy by narrowing a search. • Reflected Ultraviolet Imaging System- locates prints on nonabsorbent surfaces without chemical or powder treatments. • When UV light strikes the fingerprint, light is reflected back to the viewer- differentiating the print from its background surface.

24. Ultraviolet Imaging Systems Untreated Oily Print on sticky side of Duct (Duck) tape. 35mm Black and White film.Scene Scope excels at detecting prints on surfaces that a forensic light source would find difficult or impossible. Latent fingerprint on Painted Wall. Illustration of Contrast Effect due to variation of illumination angle. Depending on what angle the user holds the light, a print can either appear white or black.

25. Fingerprint Powders • Commercially available in a variety of colors and textures (photographing) • Lightly applied to nonabsorbent surfaces with camelhair brush will ADHERE TO PERSPIRATION RESIDUES AND BODY OILS. • Black and gray for photographing on surfaces- produce contrast.

26. Fluorescent Powders • Fluorescent powders that fluoresce under ultraviolet light- used when color or pattern of background obscures visibility of the print. (plaid, newsprint, etc). • Prints are typically not tape lifted, but photographed and digitized or transferred to a computer for analysis

27. CHEMICAL METHODS FOR VISUALIZING LATENT PRINTS Iodine fuming • Iodine is a solid crystal that when heated, turns into a vapor without passing through a liquid phase • this transformation is called sublimation. • Suspect material is placed in an enclosed cabinet with iodine crystals • Once heated, vapors fill the chamber and combine with amino acids in the latent print to make it visible. • Iodine prints are not permanent and begin to fade once fuming is stopped. The print may be “fixed” • IT IS NECESSARY TO PHOTOGRAPH IMMEDIATELY

28. Super Glue Fuming • Super Glue fuming- works great on nonporous surfaces- metals, leather, plastic bags. • Created when superglue is placed on a hot plate. • Heating produces vapors that polymerize on the print. • Produces white latent print. • The print may be enhanced with a conventional powder

29. Ninhydrin • One of the major components of fingerprints is amino acids. Several substances bind to them, but ninhydrin is particularly effective. • It is sprayed or poured onto the evidence, and a permanent pink and purple fingerprint results. • On the downside, it is toxic and causes blinding headaches if inhaled

30. Fingerprints and their use in court • The low probability of 2 unrelated prints matching is the foundation for its acceptance in court • The probability that two fingerprints could match is one in 64 billion. • This is supported by the millions of individuals who have had prints taken over the past 90 years in the FBI central system- no two have ever been found to be identical