Dna Fingerprinting : A Method Of Dna Analysis Used By Forensic Scientists

Nowadays, DNA is a crucial component of a crime scene investigation, used to both to identify perpetrators from crime scenes and to determine a suspect’s guilt or innocence (Butler, 2005). The method of constructing a distinctive “fingerprint” from an individual’s DNA was first described by Alec Jeffreys in 1985. He discovered regions of repetitions of nucleotides inherent in DNA strands that differed from person to person (now known as variable number of tandem repeats, or VNTRs), and developed a technique to adjust the length variation into a definitive identity marker (Butler, 2005). Since then, DNA fingerprinting has been refined to be an indispensible source of evidence, expanded into multiple methods befitting different types of DNA

DNA forensics is a division of forensic science that focuses on the use of genetic material in criminal investigation to answer questions pertaining to legal situations, including criminal and civil cases. Through DNA testing, law enforcement officers are able to identify human remains or the individual responsible for a crime. DNA testing is a highly advanced scientific process that involves replicating the human DNA sequence to create a genetic map of an individual. Because of its reliability, DNA testing has become a significant factor in criminal cases. However, it has also been identified as having the potential to violate privacy and constitutional rights. The DNA identification process consists of five stages. These five stages

Like fingerprints, DNA is unique, with the exception of identical twins; no two people have the same DNA. DNA profiling is a technique that can identify the person responsible of a violent

forensic identification technique today1. It is the case of analyzing and profiling a DNA sample

Basically, our DNA (deoxyribonucleic acid) is our genes, and every person, except for twins, are born with a different DNA profile and that is in a giant database, containing every DNA profile of every person in the world. DNA testing started in 1985 by scientist Alec Jeffreys and was first used to solve a crime a year later. Before 1985 DNA evidence could not be used in court because it wasn’t invented yet, this increased the number of wrongful convictions which would have been prevented using DNA analysis. However, DNA analysis can still be used to solve crimes that occurred prior to the invention of DNA analysis, with a sufficient amount of DNA to be analyzed of course, which is a very small amount. Only a small amount of DNA is needed to find out who it belongs to, it can be found in blood, saliva, finger residue, hair, skin, semen and more.

exception of identical twins, DNA fingerprinting is a reliable method used to determine the parents of a given baby. DNA fingerprints can be derived from restriction

Each person's DNA is unique . DNA biometrics technology is highly unique .The chance of two individuals having the exact same DNA is extremely impossible .Moreover ,DNA biometric technology impossible to fake because each person's DNA contains some unique trait from parents. DNA biometrics technology used in security systems but this technology is still new and it is hardly applied in public.[15]

DNA forensics can also narrow down suspect pools, exonerate innocent suspects, and link crimes together if the same DNA is found at both scenes. However, without existing suspects, a DNA profile cannot direct an investigation because current knowledge of genotype-phenotype relation is too vague for DNA phenotyping. For example, a profile from a first time offender that has no match in any database may give the information that the criminal is a left handed male of medium stature with red hair and freckles. It would be impossible to interview every man who fits that description. However, with available suspects, DNA forensics has many advantages over other forms of evidence. One is the longevity of DNA. Although it will deteriorate if exposed to sunlight, it can remain intact for centuries under proper conditions (Sachs, 2004). Because DNA is so durable, investigators can reopen old cases to reexamine evidence.

DNA profiling involves testing mini-satellites one at a time which then goes on to produce an image which is much simpler than genetic fingerprinting. It provides a pattern which is unique to a particular person and is therefore suitable for forensic purposes. (Turnpenny, P et al 2005).

DNA Fingerprinting, also known as DNA Profiling, is a method used to identify a person using DNA patterns that are specific to him/her. 99.9% of DNA is identical in every human being, but .01% is enough to distinguish between people. It is most commonly used in criminal cases to link a criminal to his/her crime scene, but is also used for paternity/maternity tests, and immigration records. Usually a skin, hair, or body fluid sample is collected from a crime scene or criminal or test candidate, then DNA is extracted and cut using enzymes that recognize patterns in DNA and run through a gel by an electric current in a process called electrophoresis (Annely).

DNA fingerprinting was introduced around 1986 to identify an alleged suspect in a rape-murder case (Panneerchelvam and Norazmi 22). Since then, using forensic DNA analysis has become more prevalent and has helped to exonerate many innocent suspects involved in such cases. Despite being used in only one percent of criminal cases, DNA tests have helped to acquit over 25 percent of wrongfully accused suspects ("Can DNA Demand a Verdict?"/Baird, Neufeld, and Scheck, 34). As of 2008, over 120 countries use some sort of forensic DNA analysis in cases like these ("INTERPOL Global DNA Profiling").

Law Enforcement keep notes on arrests that have founded people innocent of crimes, and retention of an innocent person's DNA can be charge or otherwise, seen as a invasion of that person’s privacy and civil liberties. Dr. Alec Jeffrey, a former professor at the University of Leicester laboratory, consulted with his lawyers to develop the new type of technique called DNA profiling. His technique would prove that DNA fingerprinting (profiling) can individualize evidence compared to the blood typing. DNA profiling compares 13 standard STRs to form a profile. The analysis used by the scientists, uses PCR and STRs to profile an individual. It is highly unlike that two individuals’ identical numbers of repeats for all 13 STRs, will match, which DNA fails is hardly never due to a successful match of 385 million to 1. This makes DNA profiling the most accurate tool in Forensics.

DNA fingerprinting is a technique that is used to determine how likely it is whether genetic material came from a specific person or family group. Since 99% of human DNA is identical, that means that it is only 1% of our DNA which is different, and it is that 1% that we look at when we are attempting to determine the origin of a DNA sample.

Every time somebody touches something, they leave behind a unique signature that forever links them to that object. This link is their fingerprints, which are unique to every person, for no two people have the same set, not even family members or identical twins. Palms and toes also leave prints behind, but these are far less commonly found during crime scene investigations. Therefore, fingerprints provide an identification process that is applicable to background checks, biometric security, mass disaster identification, and most importantly, crime scene investigations. Fingerprints are so differentiated because they are made up of distinct patterns of ridges and furrows on the fingers. The ridges are the “raised” portions of the prints, and the furrows are the “recessed” portions. This perceived uniqueness has led some people to falsely accept fingerprint analysis as absolute scientific fact. Although overall fingerprints are reliable, there are definitely situations where their accuracy can come into question.

The process of DNA fingerprinting in humans involves the replication and arrangement of extracted DNA, to create a pattern/fingerprint that is viable for comparison. This process involves the application of DNA extraction, digestion by restriction enzymes, Polymerase Chain Reaction (PCR) and gel electrophoresis. This results in a DNA profile with bands of varying widths that can be used for the comparison of genetic information. DNA extraction occurs in three stages. Firstly, a