DNA is a tool of great use throughout the world. Especially when it comes to the field of forensic science, DNA is the most important tool of all. What is DNA? DNA, short for deoxyribonucleic acid, is a group of molecules that hereditary information in which guides development and functioning throughout the body. “DNA is to justice as a telescope is to the stars; not a lesson in biochemistry, not a display of the wonders of magnifying glass, but a way to see things as they really are.”(Barry Scheck and Peter Neufeld, Actual Innocence) DNA profiling was first developed by two different scientists on opposite ends of the world: Sir Alec Jeffreys (UK) and Kary Mullis (US). Jeffreys came up with DNA fingerprinting and Mullis came up with a method called polymerase chain reaction (PCR). In 1984, Sir Alec Jeffreys, a professor from the University of Leicester, discovered a way of using DNA analysis through fingerprinting. () DNA fingerprinting method used variations in the genetic code in order to identify individuals. During Dr.Jeffreys’ research, he found that certain regions of DNA contained DNA sequences that were repeated over and over again. He also found that the number of repeated sequences present in a sample can differ between individuals. (John M. Butler) Fingerprinting was first used in an immigration case to determine the identity of a British boy, who was detained from his family when they had emigrated from Ghana to the United Kingdom.
The first time DNA testing was used forensically with the police was in a major case of two young girls who were sexually assaulted. In 1986 Lynda Mann and Dawn Ashworth were raped and brutally murdered. Investigators found traces of blood and semen at the sceens. Both crimes were committed in the same village which led police to determine that these crimes were committed by the same man. A man of the village had confessed to both murders. When his blood sample was compared to the semen recovered there was no match to either sample. Police were determined to find the man that did this so they conducted a mass screen to collect blood samples from every male in all the surrounding villages. Over 4000 men were tested and none of them came up as matches. A year later a woman had reported to the police that she had overheard a man bragging about how he had pretended to be his friend, Mr. Colin Pitchfork, and gave a blood sample for him. Police brought in Mr. Pitchfork for questioning and ask him for a blood sample as well.
The test results came back and determined that he was a positive match for both samples of semen that were collected from the crime scenes. Colin Pitchfork was then sentenced to life in prison. (The Blooding, 1989) During the same year, Kary Mullis with the help of the human genetics team at the Cetus Corporation came up with the PCR technique. Polymerase chain replication is a biochemical technology in molecular biology to amplify a single or a few copies of a piece of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence. At first when used Mullis didn’t want to use thermal cycling because he wanted it to react on its own but in later findings he saw that by using the thermal cycling it sped up the process. Thermal cycling of the DNA is when the samples of DNA go through cycles of heating and cooling of the DNA reaction in order for DNA melting and enzymatic replication of DNA. The first time that PCR was used was in a forensic case dealing with evidence of locus. Soon after PCR was publicized scientist began to develop many new kinds of PCR. Throughout history technology has helped to produce more ways of using DNA as a forensic tool. According to the East Midlands Forensic Pathology Unit, “although accurate and reproducible, this original method of analysis required the use of a large amount of high quality DNA, which is not always recovered during forensic investigations. Two big breakthroughs occurred during the late 1980s and early 1990s that would form the basis of DNA profiling techniques as they are recognized today.”
(East Midlands Forensic Pathology Unit, 2010) “An alternative class of DNA marker, the microsatellite or short tandem repeat (STR) marker and an alternative method for DNA visualization, PCR amplification and fluorescent labeling would greatly increase the sensitivity of DNA profiling methods and increase their use for criminal investigation,” stated Saferstein (Forensic Science: From the Crime Scene and Lab, 2012). Another new development with DNA was Hair DNA Typing. In 1996, the FBI initiated a program to compare human head and pubic hairs through mitochondrial DNA. When pulled from the head, hairs have a follicular tag, which is basically a piece of tissue surrounding the hair’s shaft near the root. This follicular tag is of great importance because that is the main source of DNA of hair. Recently in the summer of 2011, a cold-case murder of a five year old girl in 1993 was solved by using DNA hair analysis. At the time of the murder police had suspected the girl’s next door neighbor, forty-one year old Nick Stofer, but because of the lack of evidence the police could not build a case against him. Police had taken blood and hair samples from Stofer but hair DNA typing was not around at the time. According to the head detective in charge, Collins, the scent tracking dogs that had helped them to locate the body continued to follow the scent and led them back to Stofer’s house. “We wanted to put the cuffs on (Stofer) so bad, but we couldn’t because the evidence was not there,” stated Collins, “So over time, the pain, the anguish of not being able to do that kept the fire alive and it was terribly frustrating. That’s why we’re here today.
It may be therapy for us to be able to say it’s over. All of the work the police and the family and everyone put into it finally came to a conclusion.” “Over time, DNA analysis has advanced,” said Katie Featherston, forensic scientist at the Colorado Bureau of Investigation. “In 1993 it was not available at the CBI lab, but over time we have been able to deal with samples that are smaller and smaller, and/or less pristine. Those advances allowed us to do the DNA analysis on this case.” In the end Stofer was found guilty but could not be arrested because Stofer had passed away a few years before. (ABC, September 2011) The final major part of the DNA typing process is the way it is collected and preserved. If not taken care of properly the DNA will not hold up as evidence for a court case. Any piece of clothing or material that is found in a crime scene is to be taken care of lightly with minimum contact. (Criminalistics,2007) Safety considerations and the avoidance of contamination calls for the wearing of face masks, latex gloves, shoe covers, and possibly coveralls. In most forensic labs and teams, evidence is required to be photographed and collected in either a paper envelope or a plastic Ziploc bag.
According to scientist by the evidence being kept in these envelops and bags it’ll keep the evidence from being damaged. Also if there seems to be any possibility of fingerprints at the scene anything with a surface will be dusted and taken to get a genetic fingerprint to compare to in the system. (Anthony J. Bertino, Forensic Science) Since DNA typing was discovered there have been many inventions. At home DNA tests, paternity tests, genetics testing. Now a days technology is so advanced with DNA typing that women who are pregnant now can know if their baby will come out with brown, red, blonde or no hair, if their baby will have blue, green, brown, or hazel eyes. They can even find out if their child will have any genetic disorder. All because of Jeffreys’ and Mullis’ discoveries with DNA. So as you can see throughout the years DNA typing has changed drastically throughout the years. It went from being something of an experimental value to an important forensic tool. And with the help of technology it has gotten even better. Not only is the typing helpful but the DNA, itself is a major part of it. Without DNA none of these analyses would be possible. DNA has change science and the world all at the same time.
Courtney from Study Moose
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