Fingerprints

Summary What are fingerprints? How are fingerprints analyzed? How are fingerprints collected?

What are fingerprints? Friction Found on Composed of (hills) and (furrows) Black = Ridges White = Valleys

What are fingerprints? Develop in Pattern based on , detail somewhat Identical twins have fingerprints

History of Fingerprints Long history of fingerprints as signature Criminal identification first done by a system of called . Alphonse anthropometry system used body measurements to identify an individual

History of Fingerprints Sir invented a system for fingerprints Allowed fingerprint records to be Based on , so matching one print would be

How are fingerprints analyzed? Categorized by and

How are fingerprints analyzed? Patterns

Arches Arches are the simplest type of fingerprints that are formed by ridges that of the print and . Tented Arches Similar to the plain arch, but has a spike in the center. Spike or “tent” Plain Arch Ridges enter on one side and exit on the other side.

Loops Loops must have one delta and one or more ridges that . These patterns are named for their positions related to the radius and ulna bones. Radial Loop (Right Thumb) Loop opens toward the left or the radial bone. Ulnar Loop (Right Thumb) Loop opens toward right or the ulna bone. Delta NOTE: On the left hand, a loop that opens to the left would be an ulnar loop, while one that opens to the right would be a radial loop.

Whorls Whorls have at least one ridge that makes (or tends to make) a . They also have at least . If a print has more than two deltas, it is most likely an accidental. Central Pocket Whorl Plain Whorl Draw a line between the two deltas in the plain and central pocket whorls. If some of the curved ridges touch the line, it is a plain whorl. If none of the center core touches the line, it is a central pocket whorl.

Whorls – Part 2 Double Loop Whorl Double loop whorls are made up of any two loops combined into one print. Delta Accidental Whorl Accidental whorls contain two or more patterns (not including the plain arch), or does not clearly fall under any of the other categories.

How are fingerprints analyzed? Minutiae – points where Bifurcation Ridge Ending Dot Island

Ridge Characteristics Use these characteristics as points of identification when comparing fingerprint samples. The more points you can find in common, the better the match!

Ridge Characteristics Crossover Core Bifurcation (fork) Ridge ending Island Delta Pore Scar EXAMPLE http://cnx.org/content/m12574/latest/properties.jpg

compares the location of these minutiae. Fingerprints compares the location of these minutiae.

Fingerprint Identification When minutiae on two different prints match, these are called or There is for the number of points of identification required for a match However, the United Kingdom requires a minimum sixteen points while Australia requires twelve. ( ) http://www.fdle.state.fl.us/CrimeLab/images/fingerrint%20comparison%20for%20afis.jpg AFIS is a computerized system capable of reading, classifying, matching, and storing fingerprints for criminal justice agencies. Quality latent fingerprints are entered into the AFIS for a search for possible matches against the state maintained databases for fingerprint records to help establish the identity of unknown deceased persons or suspects in a criminal case.

There are 3 types of fingerprints 1. – left by Does not need processing

There are 3 types of fingerprints 2. – (butter, putty, tar, etc.) Does not need processing

There are 3 types of fingerprints 3. – requires to make visible and suitable for analysis

What are the invisible components? Fingerprints > Analysis What are the invisible components? Multiple secrete onto fingers, palms, etc. Sweat contains: Inorganic ions (Na+, Cl -) Proteins, amino acids Lipids Other

Development and Collection: Fingerprints > Analysis Development and Collection: Scene or Lab? No rule: Fingerprint after development (scene or lab)

Physical Development: Dusting Fingerprints > Analysis Physical Development: Dusting Apply to latent print or area. Powder to print. Magnetic Brush and Powder Brush and Powder

Chemical Development: Fingerprints > Analysis Chemical Development: 1. No longer used (messy, not sensitive) Silver reacts with Cl - ions in print

Chemical Development: Fingerprints > Analysis Chemical Development: 2. Iodine sublimes (solid → gas) Iodine reacts with lipid components; becomes trapped in the print. Fuming wand or chamber Dirty Brown Color

Chemical Development: Fingerprints > Analysis Chemical Development: 3. Reacts with amino acids; purple color Painted or sprayed on area Heated to react

Chemical Development: Fingerprints > Analysis Chemical Development: 4. Fumes with heat or base (NaOH) Fumed in cabinets Off-white print

Collection of prints: : Tape placed over developed print Fingerprints > Collection Collection of prints: : Tape placed over developed print Tape then placed on white card.

Collection of prints: Sometimes a photograph will be the Fingerprints > Collection Collection of prints: Sometimes a photograph will be the