Friday, August 12, 2011

Latent Fingerprint Analysis, Comparison and Evaluation


Identity recognition has been an age old problem for Law Enforcement for hundreds of years, using fingerprints technology to solve crimes and identify people allows Law Enforcement to quickly identify suspects and witnesses with circumstantial evidence that upholds the standards of trial. 

 Latent prints are created by a suspect or victim that touches an item with an uncovered hand causing it to leave a print. Friction ridges located on the hairless area on the body have small pores located in the dermis area of the skin that extend to the epidermis the first layer of skin these pores excrete sweat, oils, dirt, and other chemicals to produce a latent print.

First Principle

A fingerprint is an individual characteristic. No two fingers have identical ridge characteristics.

No two fingerprints from different subjects are the same. Meaning if a Law Enforcement agent acquirers a latent fingerprint from a subject during an investigation when scanned into the system the fingerprint will only produce one exact match no matter how many fingerprints are in the system. 

Second Principle

A fingerprint will remain unchanged during an individual’s lifetime.                                             As of  http://dhi.health.state.nm.us/eLibrary/cchspmanual/fingerprint_manual.pdf

Friction ridges or papillary ridges are formed during the third month of the fetal life, bumps called ridges are formed then points are developed to produce tactile surfaces. Unique ridged areas called minutiae form during the three month period of the fetal stage that are identifiable by fingerprints. These Friction ridges remain unchanged during a person’s life span.
The first scientist to recognize that fingerprints are unique to each subject was Sir Galton. He made up minutiae characteristics for each specific ridge line found on the hairless side of the human hand. Galton’s minutiae points described in his publication called, Finger Prints he recognized the differences in ridged areas of the finger with in his publication Galton created his own classification system called Galton Classifications, which is still in use today; it is the most common classification system for fingerprinting analysis.   

Third Principle

Fingerprints have general ridge patterns which make it possible to systematically classify.

Ridge characteristic or minutiae are described by ridge endings, bifurcations, lake or enclosures, short ridge or island, dot, spur, and crossover or bridge. These unique ridge patterns make it possible to classify fingerprints systematically.




Classification of Ridge Lines


·         Bifurcation -A single ridge that divides into two ridges

·         Ridge Ending -A ridge that abruptly ends

·         Lake or Enclosure - A single ridge that extends outward and then reunites shortly afterwards to continue as a single ridge

·         Short ridge or island or independent ridge - a ridge that commences, travels a short distance and then ends

·         Dot - An independent ridge with approximately equal length and width

·         Spur - A bifurcation with a short ridge branching off a longer ridge

·         Cross or bridge - A short ridge that runs between two parallel ridges
   
AFIS (Automated Fingerprinting Integrated System)


AFIS fingerprinting system has revolutionized fingerprint analysis in the United States of America.

How AFIS Works?


The AFIS system utilizes an automated scanning device that converts fingerprint images into digital minutiae displaying data such as ridge characteristics, and fingerprint comparison information that is vital to identifying criminal fingerprints.

The first reason why AFIS is such dynamic fingerprint utility is the fact that it is   developed to query a single database that stores fingerprint information for a given region.

The second reason is that all AFIS systems use the same algorithm for fingerprint analysis and comparison which allows it to be unified across different platforms.

The third reason why AFIS system works well is due to the reliability of uptime of the AFIS server it is up and running 24 hours a day 7 days a week. Due to the 99.9 percent uptime of the multiple disc array stripped set formatting, plus the backup mirror server of the multiple disk system allows AFIS the ability to run even when being serviced and backed up onto tape or disk. 
IAFIS the FBI’s version of AFIS links to every independent AFIS system by cities, counties, state, agencies, and local government. This system IAFIS also has the same dynamic 24 by 7 uptime as the independent AFIS systems do.

Live Scan


Utilizing FTIR Optical Frustrated Total Reflection technology allows for the Live Scan system to capture fingerprints with recognizable ridged detail. Most Live Scan systems include background information about the person being queried. Some of the newer systems use ultra sonic reflection that give ridge height details and thermal sensing that allows for an average temperature of the person who is scanning there fingerprint.

Fingerprinting is a technology that is essential to police agencies; Fingerprints are one of the best ways to identify a person without probing by performing DNA analysis. Fingerprints are harmless and interact with the skin rather than invading personal rights and performing tests, it is a quick easy method to identify a person.


References

Advances in Fingerprint Technology Second Edition, Author: Henry C. Lee and R.E. Gaensslen, Publisher: CRC Press Copyright: 2001




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