Fingerprint Identification: A Comprehensive Guide
Basic Definitions
Recognize
The mental process by which an individual associates a symbol with a meaning and vice versa.
Identify
Action and effect to identify. The process by which the characteristics of a person, animal, thing, or event are evaluated to distinguish it from others.
Individual
A procedure in which an item is different from others of their own gender. That is, unique in the universe.
Types of Individual Identification
- Civil Identification: Birth Certificate, Passport.
- Police Identification: Syllabus and Police Records.
Identification Procedures
- Identification Routine: Documents and DNA Fingerprinting.
- Identification No Routine: Forensic anthropology, forensic dentistry, Pelmatoscopia, Palmoscopia, Queiloscopia.
Fingerprinting
Etymologically, the word derives from the Greek words: daktilos = finger and skopein = test or study.
Today we know it as a branch of criminology that allows us to perform a detailed and thorough examination of the drawings formed by the ridges on the pads of the fingers to clearly identify an individual.
Fingers
They belong to the digital region of the hand, each having three phalanges, except the thumb which has only two. Movable appendages are separated from each other. They are essential organs of apprehension and touch. In normal cases, there are five: thumb, index, middle, ring, and little finger. All these fingers are constituted the same way, except the thumb which presents some anatomical peculiarities. Each finger is composed of three bones called phalanges: distal, middle, and proximal. The thumb is missing the middle phalanx.
Ridges
Epidermal reliefs are presented in the form of lines in the fingertips. The drawing formed by these lines is called a dactylogram or fingerprint.
Limitations of Crestal Systems
- Restricting Nuclear: It is the outer crest of the nuclear system that forms the inner surface of the delta or deltas.
- Restricting Marginal: The lower ridge of the marginal system that forms the inner surface of the delta or deltas.
- Restricting Basilar: The highest peak of the basilar system and contributes to the formation of the underside of the delta or deltas.
Delta
They are triangular-shaped figures resulting from the junction (fusion or approximation) of the limitations of the three crestal systems.
Types of Dactylograms
- Natural: It is that which is on the skin, a formation of stress that can be seen directly.
- Artificial Printing (Inking):
- Latent: Secretion of sweat, not visible to the naked eye, left involuntarily.
- Fingerprint Trail: The latent print once viewed, collected, or transported and activated.
- Under Stress: (Pressure on a soft surface)
Laws or Principles of Dactyloscopy
- Perennial: Fingerprint drawing is formed during fetal life (starting to form at two to three months and already complete by the sixth month) and stays with the person forever, even after life. It only disappears with the disintegration of the integument (skin).
- Immutable and Unchanged: This principle holds that the relief fingerprint, once formed, is immutable, i.e., its morphological composition cannot be altered. Regarding this issue, there is much debate about the effect generated by penetrating wounds or injury from corrosive action. However, it should be clarified that even though there may be a change in the uniformity of the dactylogram, it will never be changed by another fingerprint morphology. By contrast, the generated scar will become an individualizing part.
- Variability or Diversity of Characters: This principle argues that the way the points are arranged in a characteristic dactylogram is so diverse that it is impossible to repeat the same way because the possibility of combinations is infinite. Statistically speaking, the chances of a repeat of two identical dactylograms are zero (0).
Individualizing Characteristic Point
They are morphological particles present in the dactylogram or fingerprints. Their location and direction are highly variable, congenital, and unalterable.
Performance Points
- Steep: Papillary ridge that between two almost parallel to it ends abruptly and does not reappear.
- Bifurcation: Ridge that, following from left to right, is divided into two similar continuing ones.
- Convergence: Two ridges that, going from left to right, are merged into one.
- Deviation: Two ridges that, coming from opposite sides when approaching, stray and end independently.
- Splice: Short oblique ridge that joins at its ends to two others.
- Fragment: Portion of an isolated ridge.
- Interruption: Rupture of a ridge to twice its width.
- Loop: Ridge that bifurcates and then joins in convergence.
- Island: Fragment of circular shape.
Procedure for Making Fingerprints
The primary objective of this procedure is to obtain very clear and complete fingerprints, i.e., they observe all the drawing that the fingerprint pad has, so that they can be classified, stored, compared, and tracked.
Prior to fingerprinting, it is essential to remove sweat and foreign particles that may be on the fingers. We recommend a good washing with soap and water or detergent seconds before inking and making prints.
Place a small amount of ink spread on the piece and then beat it with the roller until a thin uniform layer is formed.
The reviewer will be placed on the right side of the person who will be reviewed and both in front of the easel or desk.
It first starts to ink the right hand, starting with the thumb and ending with the little finger, making sure to also ink each finger from one end of the pad to the other to reach the entire surface.
Necrodactyla
Known as postmortem fingerprinting, subject to the physical state of the distal phalanges of the fingers, making this one of the most important tasks during the inspection of a body for identification. Fingerprinting corpses, as well as fingerprints of violent death, is a compulsory procedure. It is recommended to take the review after all traces of potential evidence have been removed from the fingers and nails. If the state of putrefaction is advanced, a process of “reconstruction” should be carried out to ensure a clear set of footprints.
Fingerprint Anomalies
Problem
This refers to malformation, biological disorder, congenital or acquired. In terms of fingerprints, it applies to temporary or permanent disability or irregularities presented by individuals in their papillary reliefs.
These may include: Congenital, Accidental, Pathological
AFIS: Automated Fingerprint Identification System
Why an AFIS?
The aim of AFIS is to support the expert in their task of identifying persons and solving crimes.
Types of AFIS
- AFIS Criminal: Managing ten-print cards and latent prints (prints that come from crime scenes) through a computer system.
- AFIS Civilian: Included in population registration systems, issuance of identity cards, social insurance schemes. Any entity requiring secure identification to prevent fraud.
What Does an AFIS Do?
The AFIS will process the chips and traces using mathematical formulas to interpret them (not using the images to compare).
The AFIS Adds: Ten-print sheets and traces from crime scenes.
The AFIS Encodes: The traces to extract the minutiae of each finger (manually by the operator and/or automatically).
The AFIS Reasons: It allows identification based on fingerprints. It allows the linking of crimes.
Importance of Forensic Fingerprint Research
It is important for aiding and identifying the fingerprint, but it does not mean that the print is from the offender, as it is possible that a fingerprint can last for years depending on weather conditions or the maintenance of the place or scene of the crime. For example: Buying a hairdresser and the assistant moved to your room, whereas in the dresser, if he is not concerned, this helps keep the fingerprints of the assistant kept there for a long time, and then a crime happens in the room and to make or collect the traces still remain when the aide came only this time to the site.
Another example: a safe in a bank robbery is committed, and not necessarily the fingerprint to collect it from the offender, but the person who placed the amount or placed it there for some time now.