Deoxyribonucleic Acid Essay
DNA is a double helix molecule that contains information that is used to make up a person’s body. DNA controls every aspect of a person’s body from their eye and hair color, height, and other features. DNA’s specific and unique characteristic can be crucial when solving a crime. DNA can be used to convict a suspect or exonerate an innocent person. When DNA is found it is even more important that is handle properly to ensure proper identification and accuracy of testing. The evolution of DNA technology is vital to the process of solving crimes, however the process by which DNA is found and handle can jeopardize its powerfulness.
The discovery of the structure of DNA opened the realm of DNA technology which changed the way crimes can be solved. In order to understand the importance of DNA in a crime, the structure of DNA needed to be revealed first. One of the most important discoveries in history was the discovery of the structure of DNA by Watson and Crick in 1953 (Liras, 2008). This remarkable molecule contained genetic information that can be highly useful in solving a crime. DNA is the basic unit of life. The molecule uses the arrangement of bases and forms into a double helix.
This arrangement contains information and instruction for the development of the body. DNA defines each of our individual characteristics therefore making it very unique. The “arrangement of these bases in each DNA molecule is different for everyone except identical twins” (Wilson, Foreman &ump; Asplen, 1999) and this is the key to the importance of DNA evidence. DNA is everywhere in the body and remains the same and that makes DNA a very important biological evidence. The individualistic characteristic is a key feature of DNA that assists in solving a crime. No one can deny or alter their DNA since it is found in every aspect of the body.
Therefore it would be difficult for someone to defend the fact that the DNA is not his since DNA is very specific. A person’s DNA is the same no matter the source or location from on or in the body. This characteristic of DNA makes it an even more vital piece of evidence. If skins cells from dust are retrieve at a crime scene, skins cells would not have to be recollected from the suspect to prove he or she was at a location. A blood sample or cheek cells would suffice because it all contains the same DNA. DNA evidence from a crime scene can be compared from the samples taken from the suspect.
A suspect is “identified and a blood or cheek swab sample is collected and sent to the laboratory and analyzed” (Wilson, Foreman &ump; Asplen, 1999). The laboratory analyst compares the DNA information from the evidence with that of the suspect to determine if there is a match. Blood and semen are common sources of DNA evidence, but law enforcement officers are learning that other evidence can be analyzed for DNA “such as saliva, chewed tobacco or gum left behind, mucous on clothing or tissues, or skin cells left on a surface on murder weapon” (Wilson, Foreman &ump; Asplen, 1999).
All of these examples have bodily fluids that contain DNA that can crucial and narrowing down a suspect and mostly importantly convicting the guilty or freeing the innocent. DNA evidence does not have to be restricted to just blood or Semen but anything from a person’s body will contain their DNA. A suspect may not realize what valuable evidence they left behind. However, once collected and tested properly DNA evidence can seal the case. DNA technology has evolved allowing the process of testing to be more efficient and accurate. DNA testing has made some advancement since its start with ABO analysis.
This type of testing could be used determine someone’s blood type. Later, new markers for identity and paternity identification were based on “variations of serum proteins and red blood cell enzymes; eventually the human leukocyte antigen system was used” (Saad, 2005). The discovery of “fingerprint” DNA finally took DNA technology into a more advanced and accurate level of testing. Sir Alec Jeffreys, professor and geneticist at the University of Leicester in the United Kingdom was responsible for the success of DNA-based identity testing.
Professor and his team developed a “radioactive probe, made up of short sequences” that could connect onto those repeating sequences and would show patterns that were unique to each individual called a DNA “fingerprint” (Saad, 2005). DNA fingerprinting can be carried out DNA taken from the sample such as blood, semen, skin, hair. After the DNA is removed, restriction enzymes are added to cut the DNA into the smaller sections that are different for each individual. The “DNA segments are sorted by agarose gel electrophoresis and visualized by staining with ethidium bromide.
A southern blot is performed to transfer the DNA onto a membrane. A radioactive probe is applied to the membrane, and the pattern of DNA is detected by exposing the membrane to x-ray film. The result is a pattern of DNA bands that looks like a supermarket bar code. Each individual has a signature fingerprint” (Saad, 2005). The new testing made DNA a crucial evidence if found at a scene. This allowed investigators to have more solid evidence then just a blood type. Blood may not be the evidence collected therefore finding the blood type would not be an option.
Blood type is not as specific since many people can have the same blood type; however using the DNA which can be removed from multiple sources is an excellent way to confirm a match. The use of DNA “fingerprint” is highly specific; therefore a better test for accuracy and confirmation. DNA technology continued to become even more impressive with its new testing methods. After the discovery of the DNA “fingerprint”, DNA profiling was being used all over the world. DNA typing was improved with the introduction of the polymerase chain reaction (PCR) together with the discovery of different repeating sequences called microsatellites.
DNA amplification by PCR promotes increased sensitivity which allows small amounts of DNA to be tested and even from old samples (Saad, 2005). This was a huge advancement in the field of forensic because the smallest amount of DNA can be amplified to be tested. Therefore how much DNA available was no longer going to be factor in which the DNA could be analyzed and compared with the suspect. Other DNA profiling techniques, such as Restriction Fragment Length Polymorphism (RFLP) typing allowed FBI scientists to generate DNA profiles from six sites, or loci, on the DNA molecule.
These “loci provide enough information to compare with the DNA profiles from evidence stains and declare a match. Experts then compare the matching profile to various population groups and calculate the likelihood of selecting an individual from the population with a similar profile” (DNA profiling, 1998). If that number proves highly rare the suspect can be considered the match to the evidence. In addition, Improvements in RFLP typing have allowed the FBI to ”examine six loci in less than 2 weeks, a process that once took more than three times that long and involved only four sites” (DNA profiling, 1998).
The improvement in DNA testing was beneficial to the process of solving crimes. Time is always a factor when solving crimes and when evidence is available results need to be available quickly. There can be a small window of opportunity to find a suspect and a quick and accurate result can definitely make or break a case. DNA technologies have led to conviction of the guilty and exoneration of the innocent. After Professor Jeffreys made the discovery of the DNA fingerprint he was asked to use his technique in a double rape and murder case in which the suspect was admitting to one of the ases. Professor Jeffreys was asked to do DNA profiling on a blood specimen that was collected from the suspect and on tissue specimens and semen collected from the two victims. The DNA profiling revealed that the semen from both victims was identical, proving that one person had committed both murders. However, the results also proved that the suspect in police custody was not the murderer. Based on the results from the testing, he was released and became the first suspect to be cleared of a crime by DNA evidence.
A large search began to find the suspect and many samples collected in the area but still no match found. Six months later, a woman reported overhearing a man who claimed to have given blood on behalf of a colleague, Colin Pitchfork. Pitchfork was found and his blood tested; and a match was made, and Pitchfork was convicted of both murders. This successful outcome established DNA profiling as a valuable tool in solving crimes (Saad 2005). DNA was extremely important in this case and in the end convicted the guilty. It was the only evidence that confirmed the suspect as the criminal.
Although he lied the DNA evidence told the truth. DNA can also be used in freeing the innocent. Since 2007, people who were convicted of serious crimes-“including at least 14 who had been sentenced to death—have been exonerated by DNA analyses of crime scene evidence that had not been tested at the time of their trials” (Carroll 2007). Erroneous convictions can happen and new method technology can help free those who are truly innocent. The history of forensic DNA evidence certainly demonstrates the vital role DNA can play in establishing a person’s innocence or guilt. Carroll 2007). DNA evidence must be properly handled, stored and tested to maintain its powerfulness. DNA is a sensitive molecule and temperature and the containment must to correct in order to maintain its structure. It is the structure that contain the information and if alter by contamination then the result deems useless. Additional training of law enforcement personnel can help to make sure DNA is handled properly. The collection of DNA evidence must be done correctly to ensure uncontaminated sample for laboratory testing.
The storage and transport of the offender samples are issues that impact where the samples are collected and what method would be used. Cost, time and reliability are all considerations in selecting sample transportation. Vials of blood can be more expensive to transport since they require more care. DNA can be very sensitive to environment factor therefore must store carefully. If samples cannot be sent to a laboratory immediately upon collection, they must be properly stored ((Wilson, Forman, &ump; Asplen 1999).
Since DNA is such a key evidence if alter in any way it could damage the investigation completely. DNA is a powerful but sensitive structure and must be handle with care at all times. The danger of contamination is particularly great in those cases for which a technique like PCR (polymerase chain reaction) is used to multiply copies of a sequence of DNA. The amount of DNA may be too small to analyze but amplifying the DNA will help. PCR can take a small piece of sweat and turn it into a large piece of DNA that can be tested.
As a result, PCR can also amplify any contaminants along with the true signal. Tiny pieces of DNA from a technician’s sweat can be amplified as effectively as the specimen from the scene of the crime, which when could have a negative result (Dawkins 1998). Proper handling of DNA and storage is very important and even more the training of the technicians to ensure accuracy. There are other factors such as cost that can affect the process of DNA handling. Economic factors will likely have the largest effect on the implementation of DNA-related policies.
Recommendations can be made for how the criminal justice system could best use DNA technology to fight crime, but funding sources can slow the process. If funding is not available for states to reduce their current offender backlogs, databases will remain unavailable to aid law enforcement with criminal investigations. . It is up to the criminal justice system is to realize the “full potential of DNA evidence as a crime fighting tool” (Wilson, Forman, &ump; Asplen 1999), efforts must be made both to solve the database backlog of today and to promote DNA evidence use throughout all levels of law enforcement.
As criminals become cleverer, evidence like DNA becomes even more important. The discovery of DNA has truly helped in solving crimes and has proven to be vital evidence. However it can not be as powerful as it should if not handled or tested properly. DNA technology is still advancing and only time will time will reveal what will be available in the future.
University/College: University of Chicago
Type of paper: Thesis/Dissertation Chapter
Date: 3 November 2016
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