next to a quarter. 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
fingerprints. This assertion is supported by the philosophy of
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: • Friction ridges develop on the fetus in their definitive form prior to birth. • Friction ridges are persistent throughout life except for permanent scarring, disease, or decomposition after death. • Friction ridge paths and the details in small areas of friction ridges are unique and never repeated. • 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 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. 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. Those who specialize in forensic identification continue to make headway with new discoveries and technological advances to make convictions more accurate.
Body identification is a subfield of forensics concerned with identifying someone from their remains, usually from
fingerprint analysis, dental analysis, or
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. These creases are valuable when individualizing the owner. The concept of no two fingerprints are alike is also applied to foot creases. 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. 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. 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. 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. The belief was passed down through generations being generally accepted, but it was never scientifically proven. There was a study done intending to show that no two fingerprints were the same, but the results were inconclusive. Many modern forensic and
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.
Primary methods According to Interpol, 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. 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. 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.
DNA identification Forensic
DNA analysis can be a useful tool in aiding forensic identification because DNA is found in almost all cells of the body except mature red blood cells.
Deoxyribonucleic acid is located in two different places of the cell, the
nucleus; which is inherited from both parents, and the
mitochondria; inherited maternally. As with fingerprints, an individual's
DNA profile and characteristics are unique. 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. A
forensic scientist can attempt to obtain a DNA profile from the sample with as few as six cells. 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. 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. 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. == Animal identification ==