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How does DNA help in solving crimes
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DNA, otherwise known as Deoxyribonucleic acid, is a fundamental part of our body, providing genetical information to cells, determining our genetic genotypes and visible phenotype characteristics. It also has other uses, such as DNA Fingerprinting. This technique requires a sample of cells, that, through a scientific process, produce a unique pattern to determine a person by. DNA fingerprinting is used in paternity testing, to determine a child’s father, and in forensics and crime solving. The science behind DNA fingerprinting in forensics, and moral dilemmas surrounding it, will be explored and explained.
DNA fingerprinting requires a sample of cells. For example, a drop of blood left on a crime scene by the assumed culprit. From these cells, DNA is extracted and cut into smaller pieces using ‘restriction enzymes.’ These restriction enzymes are proteins that, when removed from the bacterial cell they grow on, are used to cut DNA. Once the DNA has been cropped into some thousand smaller pieces of varying length, the pieces are put in a gel, in one pile.
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An electric current is passed through the gel, is one side carrying a positive charge and the other side carrying a negative charge. DNA, being negatively charged, works like a magnet, and moves toward the positively charged electric end of the gel. In a magnet, opposites attract, so the negatively charged DNA moves to the positively charged electric current. However, the smaller pieces of DNA move faster, so when the electricity is quickly turned off, the shorter parts have moved to the positively charged end, the larger parts have stayed where they are, and the middle pieces are in-between. Hence, the DNA pieces are sorted per
The gels were run at 90-100 volts for 1-1.5 hours. Upon completion of the experiment, we were able to examine the DNA. First, the electrophorese. revealed that three of the fourteen samples were homozygous while the other eleven were
DNA is the blueprint of life. It stores our genetic information which is what is in charge of how our physical appearance will look like. 99.9% of human DNA is the same in every person yet the remaining .1% is what distinguishes each person (Noble Prize). This small percentage is enough to make each person different and it makes identifying people a lot easier when its necessary. DNA not only serves to test relationships between people it also helps in criminal cases. DNA testing in criminal cases has not been around for many years if fact it was not until the early 1990s when the use of DNA testing for criminal cases was approved and made available. By comparing the DNA of a suspect and that found in the crime scene a person can either be convicted of a crime or they can be exonerated. This method of testing gained more publicity in the 1984 case of Kirk Noble Bloodsworth a man who had been convicted of the rape and first degree murder of a nine year old girl in Maryland. His case was a milestone in the criminal justice system since it involved the use of new technology and it also raised the question of how many people had been wrongly incarcerated for a crime they did not commit.
. DNA can be left or collected from the hair, saliva, blood, mucus, semen, urine, fecal matter, and even the bones. DNA analysis has been the most recent technique employed by the forensic science community to identify a suspect or victim since the use of fingerprinting. Moreover, since the introduction of this new technique, there has been a large number of individuals released or convicted of crimes based on DNA left at the crime scene. DNA is the abbreviation for deoxyribonucleic acid.
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 samples. One of the more controversial practices of DNA forensics is familial DNA searching, which takes partial, rather than exact, matches between crime scene DNA and DNA stored in a public database as possible leads for further examination and information about the suspect. Using familial DNA searching for investigative purposes is a reliable and advantageous method to convict criminals.
One of society’s problems is that the wrong people are convicted of a crime they did not commit. None have more dire consequences on those than who are wrongly convicted of rape and murder. The punishment for these crimes are as harsh as possible to deter the crimes and when wrongly convicted, the wrong person gets punished while the true perpetrator gets away. In order to increase the chance of convicting the true perpetrator of the crime, the tools to find and convict criminals had to be refined. And it was refined due to extensive research into DNA. This research was done by Alec Jeffreys and Vicky Wilson, the research’s technician, and it found that in the massive amount of junk codes, there exists many repetitious codes that have copied so many times that it varies from person to person. (Ridley 132) This means that people can be identified with only their DNA from their hair, fluids, skin, etc. This discovery has led to convictions of rapists and murderers such as the Pickford case that Ridley wrote about. It has also led to the sentences of many wrongly convicted people to be retracted and this had led to the release of about 200 people known as the DNA 200. (Phelan) Now, most of the world keeps criminals’ genotype information in order to identify repeat offenders. In the United States, every state requires that every convicted
Abstract; This paper explors the effects DNA fingerprinting has had on the trial courts and legal institutions. Judge Joseph Harris states that it is the "single greatest advance in the search for truth since the advent of the cross examination (Gest, 1988)." And I tend to agree with Judge Joseph's assertion, but with the invention and implementation of DNA profiling and technology has come numerous problems. This paper will explore: how DNA evidence was introduced into the trial courts, the effects of DNA evidence on the jury system and the future of DNA evidence in the trial courts.
The Innocence Project, using DNA evidence, has gone back to past cases and exonerated innocent people when they were wrongly convicted. There may be many reasons that several people are wrongly convicted every year. However, there are 6 reasons deemed as the most important regarding wrongful convictions. These reasons are eyewitness misidentification, unvalidated or improper forensic science, false confessions or admissions, government misconduct, informants or snitches, and bad lawyering (understand the causes).
Before the late 1800’s, DNA was never used in court cases. We did not have the equipment readily available. Then, in the late 1800’s and early 1900’s, DNA testing started to become very popular. This is when cases started getting overturned from wrongful court convictions. Which meant that the criminal that had actually committed the crime was on the loose in the community still able to do harm. In today’s generation, we still have many wrongful court convictions. Either due to their being little to no DNA evidence in the beginning of their case or the DNA evidence was tested incorrectly or possibly tampered with and that is what lead to the conviction of the wrong person. With the high level of technology we have today and the highly skilled experts in the labs we shouldn’t have any wrongful convictions. While we
DNA fingerprinting, or sometimes known as DNA typing, is isolating and developing images of sequences of DNA to evaluate the DNA in an individual’s cells. DNA fingerprinting today is used for many different things in many different areas of science. In forensic science, DNA typing can determine which person did which crime by using blood or skin left at a crime scene. In medical science, patients can find out who their siblings, parents, or children are by using DNA fingerprinting (webmd).
DNA in forensic science has been around for a long time. DNA has had help in solving almost every crime committed. There have been a lot of crimes where people are raped or murdered and the person who did it runs free. Scientists can collect the littlest item they see at the scene, such as a cigarette butt or coffee cup and check it for DNA. People have spent years in jail for a crime they didn’t commit till DNA testing came into effect. People are getting out of jail after 20 years for a crime they didn’t commit, cause of the DNA testing. DNA has helped medical researchers develop vaccines for disease causing microbe. DNA has become a standard tool of forensics in many murders and rapes.
DNA, or deoxyribonucleic exists in all living organisms, is self-replicating and gives a person their unique characteristics. No two people have the same matching DNA. There are many different forms of DNA that are tested for situations such as criminal. Bodily fluids, hair follicles and bone tissues are some of the most common types of DNA that is tested in crime labs today. Although the discovery of DNA dates back to 1866 when Gregor Mendel proved the inheritance of factors in pea plants, DNA testing is relatively new and have been the prime factor when solving crimes in general. In 1966, scientists discovered a genetic code that made it possible to predict characteristics by studying DNA. This lead to genetic engineering and genetic counseling. In 1980, Organ was the first to have a conviction based off DNA fingerprinting and DNA testing in forensics cases became famous in 1995 during the O.J. Simpson trial (SMC History , 2011).
Forensic genetics has other applications . The " fingerprint " DNA represents a valuable tool for forensic science . As is the case with an ordinary fingerprint genetic fingerprint is unique to each individual (except identical twins ) . The determination involves the observation of specific DNA sequences which can be obtained from extremely small tissue samples , hair, blood or eventually left at the scene . As Fifty microliters of blood, semen or five microliters of ten roots of hairs are enough , and nozzles secretions and cells from the fetus . In addition to its use in the capture of criminals , especially rapists , the genetic fingerprints can be used to establish family relationships . People involved in the conservation of species use them to be sure that captive breeding is among individuals who do not belong to the same family .
Once a crime has been committed the most important item to recover is any type of evidence left at the scene. If the suspect left any Deoxyribonucleic acid (DNA) at the crime scene, he could then be linked to the crime and eventually charged. A suspect’s DNA can be recovered if the suspect leaves a sample of his or her DNA at the crime scene. However, this method was not always used to track down a suspect. Not too long ago, detectives used to use bite marks, blood stain detection, blood grouping as the primary tool to identify a suspect. DNA can be left or collected from the hair, saliva, blood, mucus, semen, urine, fecal matter, and even the bones. DNA analysis has been the most recent technique employed by the forensic science community to identify a suspect or victim since the use of fingerprinting. Moreover, since the introduction of this new technique it has been a la...
Deoxyribonucleic acid (DNA) is an acclaimed extraordinary discovery that has contributed great benefits in several fields throughout the world. DNA evidence is accounted for in the majority of cases presented in the criminal justice system. It is known as our very own unique genetic fingerprint; “a chromosome molecule which carries genetic coding unique to each person with the only exception of identical twins (that is why it is also called 'DNA fingerprinting ')” (Duhaime, n.d.). DNA is found in the nuclei of cells of nearly all living things.
Before the 1980s, courts relied on testimony and eyewitness accounts as a main source of evidence. Notoriously unreliable, these techniques have since faded away to the stunning reliability of DNA forensics. In 1984, British geneticist Alec Jeffreys of the University of Leicester discovered an interesting new marker in the human genome. Most DNA information is the same in every human, but the junk code between genes is unique to every person. Junk DNA used for investigative purposes can be found in blood, saliva, perspiration, sexual fluid, skin tissue, bone marrow, dental pulp, and hair follicles (Butler, 2011). By analyzing this junk code, Jeffreys found certain sequences of 10 to 100 base pairs repeated multiple times. These tandem repeats are also the same for all people, but the number of repetitions is highly variable. Before this discovery, a drop of blood at a crime scene could only reveal a person’s blood type, plus a few proteins unique to certain people. Now DNA forensics can expose a person’s gender, race, susceptibility to diseases, and even propensity for high aggression or drug abuse (Butler, 2011). More importantly, the certainty of DNA evidence is extremely powerful in court. Astounded at this technology’s almost perfect accuracy, the FBI changed the name of its Serology Unit to the DNA Analysis Unit in 1988 when they began accepting requests for DNA comparisons (Using DNA to Solve Crimes, 2014).