Forensic identification
Friction ridge identification is also governed by four premises or statements of facts: People can also be identified from traces of their DNA from blood, skin, hair, saliva, and semen[1] by DNA fingerprinting, from their ear print, from their teeth or bite by forensic odontology, from a photograph or a video recording by facial recognition systems, from the video recording of their walk by gait analysis, from an audio recording by voice analysis, from their handwriting by handwriting analysis, from the content of their writings by their writing style (e.g. typical phrases, factual bias, and/or misspellings of words), or from other traces using other biometric techniques.
A lot of trials have been reviewed and testimony involving mostly microscopic hair comparison, but also bite mark, shoe print, soil, fiber, and fingerprint comparisons have been overturned because forensic analysts have provided invalid testimony at the trial.
Feet have creases which remain over time due to the depth it reaches in the dermal layer of the skin, making them permanent.
[2] This individualization belief was invented by a police records clerk, Alphonse Bertillon, based on the idea that "nature never repeats," originating from the father of social statistics, Lambert Adolphe Jacques Quetelet.
Fingerprints from the hands and feet are unique and remain unchanged (unless major external factors are involved) from birth to death.
[14] Forensic odontology (dentistry) plays an important role in human identification, especially in cases where individuals are in an advanced stage of decomposition, charred, or skeletonized.
This is due to the high resistance of teeth, which can remain intact even after exposure to harsh conditions.
When a sample is located at a crime scene, it must be collected, processed, and transported, along with a chain of custody, to the laboratory for analysis, so that if a DNA profile is generated it can be accepted in court.
DNA can be sourced from biological material such as semen, blood, saliva, feces, urine, teeth, bone, and hair that is left behind from an individual.
Presumptive tests are quick, sensitive and are relatively specific to bodily fluids that give the analyst an idea of what might be present.
In addition to looking for biological material at a crime scene, pieces of evidence can also be examined and analyzed for the presence of DNA.
Evidence pieces that may have the presence of DNA could include clothing, bedding, weapons, masks, gloves, among many others.
CODIS/NDIS allows analysts to compare their questioned DNA profile among those of arrestees, convicted offenders, and other unknown samples to try and produce investigative leads.
STR is common in forensic analysis because they are easily amplified using polymerase chain reaction (PCR) and they have unique variation among individuals for human identification.
DNA profiling is one of the most important tools in forensics and continued research will increase its ability and accuracy to provide more techniques for the future.
[28] That being said, the comparison process demands precision because mistakes can easily be made due to genes evolving and mutating in the evolution of species.
[31] In addition to phylogenetic data, assignment tests are used to find the probability of a species belonging to or originating from a specific population and genetic markers of a specimen are utilized.
Statistical analyses are used in assignment tests based on an individual's microsatellites or Amplified Fragment Length Polymorphisms (AFLPs).
[36][38] Domestic animals such as dogs and cats can be utilized to help solve criminal cases.
[41] In the competitive realm, DNA analysis is used in many cases to find illegal substances in racehorses by urine samples and comparisons of STRs.
[42][43][44] Sometimes, manufacturers and film distributors may intentionally leave subtle forensic markings on their products to identify them in case of piracy or involvement in a crime.
