A trained fingerprint examiner makes that assessment by comparing details including the shapes that the ridge lines form and where the lines end or split. Latent prints are often partial, distorted or smudged, so the first step is to determine if there is sufficient detail in the latent print to make a comparison.
Fingerprinting, also referred to as mapping or scene analysis, is a method of mapping the measured data (e.g., RSS) to a known grid point in the environment represented by a data fingerprint. The data fingerprint is generated by the environment site-survey process during the off-line system calibration phase.
The most common method is through optical scaning, which use prisms to measure the distance between the tiny ridges and valleys which form a fingerprint image. Another method uses thin film transistor (TFT) technology, which employs a small electrical current to measure those same ridges and valleys.
Fingerprint identification is known officially as dactyloscopy, which is the process of examining and comparing separate ridge skin impressions to determine whether they came from the same person.
The three principles of fingerprints are: Individual characteristic - No two fingers have the same pattern. Remain unchanged - A fingerprint will not change during an individual's lifetime. Unique patterns - Fingerprints have general patterns which make it possible to classify them as "arch, loop, or whorl."
Fingerprint friction ridge details are generally described in a hierarchical order at three levels, namely, Level 1 (pattern), Level 2 (minutiae points) and Level 3 (pores and ridge shape).
There are three main fingerprint patterns, called arches, loops and whorls. The shape, size, number and arrangement of minor details in these patterns make each fingerprint unique.
Law enforcement has relied on fingerprint analysis to identify suspects and solve crimes for more than 100 years. Investigators use fingerprints to link a perpetrator to a crime scene. Individual fingerprint identification records have also been used in sentencing, probation, and parole decisions.
Traditional forensic analysis methods include the following: Chromatography, spectroscopy, hair and fiber analysis, and serology (such as DNA examination)
One of the most important uses for fingerprints is to help investigators link one crime scene to another involving the same person. Fingerprint identification also helps investigators to track a criminal's record, their previous arrests and convictions, to aid in sentencing, probation, parole and pardoning decisions.
A magnifier (Figure 11–8) is a basic piece of equipment for comparing latent prints. A good fingerprint magnifier is a solidly built magnifying glass that has an adjustable eyepiece to allow for individual eyesight variations. Magnification is typically 4.5X with the use of good lighting (Olsen, 1978, pp 171–175).
Individual characteristics of each fingertip
This first fundamental principle of fingerprints describes their uniqueness. According to this principle, a fingerprint is an individual characteristic and no two fingers are found to have identical ridge patterns.
Digesting the DNA with the help of restriction endonuclease enzymes. Separating the digested fragments as per the fragment size by the process of electrophoresis. Blotting the separated fragments onto synthetic membranes like nylon. Hybridising the fragments using labelled VNTR probes.
The five basic steps in the crime analysis process include the collection, categorization, analysis, dissemination, and evaluation of information. The reports and forms for use in each step of information-gathering and analysis are explained and illustrated.
The general phases of the forensic process are: the identification of potential evidence; the acquisition of that evidence; analysis of the evidence; and production of a report.
It turns out that there's room for error. One accuracy study found that analysts make false positive matches (saying two prints are the same when they're not) in 0.1% of cases. That may seem pretty good, but it can be a huge problem when an innocent person is wrongfully convicted of a crime based on a false match.
One known flaw in fingerprinting is that examiners may taint the identification process through bias and peer pressure.
In these instances, no conclusion can be made and the report will read “inconclusive.” The three possible results that can be made from a fingerprint examination are therefore exclusion, identification, or inconclusive.
Today police in most countries use such systems, called automated fingerprint identification systems (AFIS), to search rapidly through millions of digitized fingerprint records. Fingerprints recognized by AFIS are examined by a fingerprint analyst before a positive identification or match is made.
Fingerprint Characteristics
The three characteristics are arches, whorls, and loops.
The Federal Bureau of Investigation (FBI) recognizes eight different types of fingerprint patterns: radial loop, ulnar loop, double loop, central pocket loop, plain arch, tented arch, plain whorl, and accidental.
The two underlying premises of fingerprint identification are uniqueness and persistence (permanence). To date, no two people have ever been found to have the same fingerprints—including identical twins. In addition, no single person has ever been found to have the same fingerprint on multiple fingers.