Approaches to forensic tools and procedures for absolute human identification based on physical and molecular principles

The purpose of most crime or civil cases is absolute human identity, such as murder, sexual assault, kidnapping, disputed paternity, establishing familial linkage, migration cases, burglary, identifying of unidentified, and many others. The major goal in these situations is to identify the accused person and link the victim and/or suspect to the crime. As a result, forensic instruments and techniques for absolute human identification play an integral role in crime investigation. In crime scene investigation, the two most prevalent physical and molecular identification and authentication procedures are used.

For over a century, forensic fingerprint analysis has been used to identify criminals. There are no two fingerprints that are identical. Fingerprint identification and classification techniques were established in the late 1800s, and fingerprint evidence was first recognised in British courts in 1901 the process begins with a deposited, or “latent,” print discovered at the crime scene. Fingerprint analysts visually match the latent print from the crime scene to the fingerprint of a suspect if the print is detailed enough. A friction ridge print can produce three different sorts of fingerprints (pattern in a medium). Patent or apparent, plastic, and latent are examples of these categories. Patent prints are easy to spot because they are visible to the naked eye. The method utilised to gather fingerprint evidence is frequently determined by the type of surface being examined or searched for fingerprints. Porous surfaces, non-porous surfaces, and human skin are examples of these surfaces.

DNA fingerprinting, a molecular approach, has become the most powerful technique for the court system to aid in the conviction of the guilty as well as the exoneration of the innocent. At the University of Leicester, the term “DNA fingerprinting” or “genetic profiling” was coined 25 years ago. DNA fingerprinting was invented in 1984 by Professor Sir Alec Jeffreys. DNA fingerprinting is a laboratory technique that uses the nucleotide sequences of certain areas of human DNA that are unique to individuals to identify a person’s probable identification. DNA fingerprinting is utilised in a variety of contexts, including criminal investigations, forensic investigations, and paternity testing. In these cases, the goal is to “match” two DNA fingerprints, such as a known person’s DNA sample and an unknown person’s DNA sample.

By assessing the probability of a match occurring by chance, DNA samples can be compared to offer evidence for forensic investigation and identification of an individual. A DNA profile can inform a scientist if the DNA belongs to a male or a female, and which individual the sample being examined belongs to. A person’s DNA profile is formed by both his and her father and mother. There are 23 chromosomes from the father and 23 chromosomes from the mother, resulting in a child with 23 pairs of chromosomes.

Restriction fragment length polymorphism is a standard approach for DNA fingerprinting (RFLP). DNA is taken from a sample and cut into segments using particular restriction enzymes in this process. RFLP focuses on regions that contain repeating DNA base sequences that differ greatly from person to person. Electrophoresis, a laboratory technique for sorting fragments by length, is used to separate the segments. The segments are radioactively tagged, resulting in a visible pattern on X-ray film known as an autoradiograph, or DNA fingerprint. Short tandem repeats (STR) is a recent approach that examines DNA segments for the number of repeats at 13 specified DNA locations.

SS Daga, Umema Ahmed and RK Kumawat shows the potential utility of both methodologies for criminal investigation and a comparative assessment of these approaches in their research on “Forensic Tools and Techniques of Absolute Human Identification: Physical and  Molecular Approach”.

Reference: SS Daga, Umema A, RK Kumawat. Forensic Tools and Techniques of Absolute Human Identification: Physical and Molecular Approach. J Forensic Sci & Criminal Inves. 2021; 15(3): 555913.  DOI: 10.19080/JFSCI.2021.15.555913

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