Forensic identification

Source: Wikipedia, the free encyclopedia.

Forensic identification is the application of forensic science, or "forensics", and technology to identify specific objects from the trace evidence they leave, often at a crime scene or the scene of an accident. Forensic means "for the courts".

Human identification

human blood. In addition to analyzing for DNA
, the droplets are round and show no spattering, indicating they impacted at a relatively slow velocity, in this case from a height of two feet.

People can be identified by their

friction ridge
identification, which states that friction ridge identification is established through the agreement of friction ridge formations, in sequence, having sufficient uniqueness to individualize.

Friction ridge identification is also governed by four premises or statements of facts:

  1. Friction ridges develop on the fetus in their definitive form prior to birth.
  2. Friction ridges are persistent throughout life except for permanent scarring, disease, or decomposition after death.
  3. Friction ridge paths and the details in small areas of friction ridges are unique and never repeated.
  4. Overall, friction ridge patterns vary within limits which allow for classification.

People can also be identified from traces of their DNA from blood, skin, hair, saliva, and semen

biometric
techniques. Many methods that are used in forensic science evidence have been proven to be unreliable. 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.

Since forensic identification has been first introduced to the courts in 1980, the first exoneration due to DNA evidence was in 1989 and there have been 336 additional exonerations since then.[2][3] Those who specialize in forensic identification continue to make headway with new discoveries and technological advances to make convictions more accurate.[4][5]

DNA analysis
.

Foot creases

Feet also have friction ridges like fingerprints do. Friction ridges have been widely accepted as a form of identification with fingerprints but not entirely with feet. Feet have creases which remain over time due to the depth it reaches in the dermal layer of the skin, making them permanent.[6] These creases are valuable when individualizing the owner. The concept of no two fingerprints are alike is also applied to foot creases.[7] Foot creases can grow as early as 13 weeks after conception when the volar pads begin to grow and when the pads regress, the creases remain.[8][9] When foot crease identification is used in a criminal case, it should be used in conjunction with morphology and friction ridges to ensure precise identification. There is record of foot crease identification used in a criminal case to solve a murder.[6][10] Sometimes with marks left by the foot with ink, blood, mud, or other substances, the appearance of creases or ridges become muddled or extra creases may appear due to cracked skin, folded skin, or fissures. In order to truly compare morphological feature, the prints of feet must be clear enough to distinguish between individuals.

Downfalls

The two basic conceptual foundations of forensic identification are that everyone is individualized and unique.

evidentiary scholars collectively agree that individualization to one object, such as a fingerprint, bite mark, handwriting, or ear mark is not possible. In court cases, forensic scientists can fall victim to observer bias when not sufficiently blinded to the case or results of other pertinent tests. This has happened in cases like United States v. Green and State v. Langill. Also, the proficiency tests that forensic analysts must do are often not as demanding to be considered admissible in court.[citation needed
]

Primary methods

According to Interpol,[13] there are 3 primary methods to human identification: Friction Ridge Analysis, Forensic Odontology, and DNA Analysis.

Friction ridge analysis

Fingerprints from the hands and feet are unique and remain unchanged (unless major external factors are involved) from birth to death. Even with minor injuries, they regenerate following the same pattern. [14]

Considering the existence of databases in states and countries worldwide containing records of fingerprints from their residents, there is the possibility of searching and comparing fingerprints. This enables an accurate comparison for victim identification. [14]

Odontology analysis

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.[14]

Considering that many people have visited a dentist and have dental records, there is the possibility of retrieving this data for comparison with post-mortem examination data. Such a method enables quick, cost-effective, and reliable identification.[14][15][16]

The most commonly used ante-mortem data are dental X-rays, dental models, and dental records. However, these data rely on the existence of dental records registered by a dentist. Nevertheless, even if a person does not have such records, a photograph of their smile or an old dental prosthesis can be used for comparison.[15][16][17][18][19][20]

DNA identification

Forensic

DNA profile and characteristics are unique.[citation needed] Forensic identification using DNA can be useful in different cases such as determining suspects in violent crimes, solving paternity/maternity, and identifying human remains of victims from mass disasters or missing person cases.[21]
It is also used to link suspects or victims to each other or to crime scenes. 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. Proper evidence collection and preservation is crucial to ensure evidence is not being contaminated. Main procedures investigators must use when packaging biological material is allowing the evidence to air dry and then package into paper bags. Plastic bags should never be used on biological evidence because it could degrade DNA or lead to bacterial growth.

DNA can be sourced from

forensic scientist can attempt to obtain a DNA profile from the sample with as few as six cells.[22]

The first step in the DNA process with a piece of evidence is

amplification in order to yield multiple copies of DNA. Next is separation, to separate the DNA out to use for identification. Finally, the analyst can now complete analysis and interpretation of the DNA sample and compare to known profiles.[23]

An unknown sample found at a crime scene is called a questioned sample. A known sample can be taken either from a suspect or found in a database. The FBI’s database used for DNA is CODIS, Combined DNA Index System. It has data at three levels: local, state, and national. The national level data is stored in NDIS, National DNA Index system. 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.[24] If questioned and known samples are similar, statistics and interpretation will then be completed. The DNA profile will be compared to a population database and a random match probability will be determined. Random match probability is defined as the chance that an individual selected randomly from a population will have an identical DNA profile to the markers tested.[21] If they do not equal each other, they are not a match, termed exclusion.

During

DNA typing, several markers are examined, termed loci. When more markers are examined, this could result in either a greater probability that two unrelated individuals will have different genotypes or adds to the confidence of connecting an individual to an unknown sample.[21]
One locus difference between a questioned and known sample is enough to exclude that suspect as the contributor.

The

short tandem repeats which are short DNA regions in the genome and are 2-6 base pairs in length. 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. PCR is the technique of copying DNA by making millions of copies. When all 13 core loci are tested on a DNA profile, the random match probability is more than one in a trillion.[21]

Since DNA was first used in a criminal investigation in 1986, it has aided investigators to solve many cases. 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.[25]

Animal identification

Wildlife forensics

There are many different applications for

wildlife forensics
and below are only some of the procedures and processes used to distinguish species.

Species identification: The importance of

species identification is most prominent in animal populations that are illegally hunted, harvested, and traded,[26] such as rhinoceroses, lions, and African elephants. In order to distinguish which species is which, mtDNA, or mitochondrial DNA, is the most used genetic marker because it is easier to type from highly decomposed and processed tissue compared to nuclear DNA.[27] Additionally, the mitochondrial DNA has multiple copies per cell,[27] which is another reason it's frequently used. When nuclear DNA is used, certain segments of the strands are amplified in order to compare those to segments of mitochondrial DNA. This comparison is used to figure out related genes and species proximity since distant relatives of animals are closer in proximity in the gene tree.[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.[29]

Determination of geographic origin: Determining the origin of a certain species aids research in population numbers and lineage data.[26] Phylogenetic studies are most often used to find the broad geographic area of which a species reside.[30] For example, in California seahorses were being sold for traditional medicinal purposes and the phylogenetic data of those seahorses led researchers to find their origin and from which population they came from and what species they were.[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.[32][33][34][35] These types of tests are most accurate when all potential population's data have been gathered. Statistical analyses are used in assignment tests based on an individual's microsatellites or Amplified Fragment Length Polymorphisms (AFLPs).[32][35][36][37] Using microsatellites in these studies is more favorable than AFLPs because the AFLPs required non-degraded tissue samples and higher errors have been reported when using AFLPs.[36][38]

Domestic animal forensics

Domestic animals such as dogs and cats can be utilized to help solve criminal cases. These can include homicides, sexual assaults, or robberies. DNA evidence from dogs alone have helped over 20 criminal cases in Great Britain and the U.S. since 1996.[39] However, there are very few laboratories that are able to process and analyze evidence or data from domestic animals.[40] Forensics can be used in animal attacks as well. In cases such as dog attacks, the hair, blood, and saliva surrounding the wounds a victim has can be analyzed to find a match for the attacker.[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]

Product identification

Networks

Applications

Sometimes,

.)

Organizations

See also

References

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External links