Dna, Evidence, And Dna Evidence

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

I. Before the 1980’s, 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.

Beginning in the mid-1980s, the development of DNA analysis technology has revolutionised the field of forensic science within the criminal justice system. As the refinement of procedures and technology continues, even minute samples of biological material (including blood, saliva, semen and skin cells) are able to be analysed and used to link or acquit perpetrators of crimes. (Whitney, R n.d.)

Today in the crime world, DNA evidence is strongly accepted in solving crime cases. This is all based in part by allowing a crime laboratory to have a designated unit whose main goal is to analyze DNA evidence to aid investigators with positive outcomes in crime case solving. With that being said we are going to discuss the functions of a DNA unit within a crime lab as well as address the vital role these units play in solving crime.

Due to the uniqueness of DNA it has become a powerful tool in criminal investigations

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.

In November of 1983, 15 year old Lynda Mann was found raped and murdered on a deserted road, and although police were able to obtain a semen sample from her murderer the case remained unsolved. In 1986 the killer struck again murdering 15 year old Dawn Ashworth, once again leaving behind semen, but this time the police were able to use DNA profiling to match the semen to a suspect. Colin Pitchfork became the first person to be caught based on mass DNA screening, and the first to be convicted based on DNA profiling. The use of Deoxyribonucleic Acid (DNA) in the criminal justice system has greatly tipped the scales in favor of law enforcement, and changed the world that we live in. Court cases that in the past relied heavily on eye witness testimony and circumstantial evidence now have science to back them up. DNA analysis has revolutionized the criminal justice system, and even though there are some flaws, the use of DNA evidence should continue to be used by law enforcement.

Identification means the steps needed in the analysis of unknown fluids to see what the substance is (“Biology,” 2016). Individualization determines whether a certain individual may or may not be the donor of a bodily substance by examining various markers (“Biology,” 2016). Processing biological trace evidence uses highly complex, automated technology to create a DNA profile that helps the investigators through the association of suspects to victims and to crime scenes (“Biology Services,” 2017). By using techniques such as polymerase chain reaction (PCR), forensic biologists can use variable markers found on the regular chromosomes (STR’s), the sex chromosomes (Y-STR’s) and within the mitochondrial DNA to distinguish one person’s DNA from another to a high degree of certainty (“Biology,” 2016). Forensic biologists are involved in assisting investigative agencies because police were led to Bernardo by a police sketch (“Serial Killers: Paul Bernardo and Karla Homolka,” 2013). The police took DNA (hair, blood and saliva) from Bernardo as a matter of routine to test it against specimens found on a rape victim’s clothing (Butts, n.d.). Forensic biologists were able to name the substances left on Kristen French’s body and match it to Bernardo’s DNA by processing it. On February 17th, 1995, Bernardo was arrested for the murders of Mahaffy, French, and the Scarborough rapes (Butts,

There are many sources of DNA for testing. Blood is one of the key sources, though the surface on which a bloodstain is found can profoundly affect the ability to successfully perform an analysis. In addition, bloodstains may be mixtures of blood from two different people and can produce DNA profiles that are more complex than those from a single individual. Ironically, DNA profiling may be the only way to determine if a given stain is a mixture. Semen stains are the most common evidence to be submitted for DNA analysis, which is not surprising since the cases in which DNA testing has been used the most often are rapes. DNA can also be extracted from tissues (taken at autopsy), hair roots, saliva, and in rare instances, urine.(4) It is important to note that only a miniscule amount of DNA is needed for analysis. For example, the amount of DNA found at the root of one hair is usually sufficient. Environmental factors also play a role in determining whether a particular sample of DNA can be utilized. Moisture, sunlight, bacterial action and heat are detrimental to the DNA. Depending on the intensity and combination of these conditions, survival of the DNA is measured in weeks or months. Even so, DNA in usable amounts can

How has DNA evidence helped to identify innocent people on death row? This research topic addresses questions like how many people have been released on death row, where DNA evidence is found, and how the person looking for the DNA finds it. The researcher has to think in a way if obvious evidence isn’t present at a crime scene, where else can they find evidence? This topic of identifying innocent people on death row is important to research because many people are accused of crimes they haven’t committed and automatically put on death row. When researching this topic DNA evidence could be found as helpful to solve crimes and find out what really happened in a situation. Before DNA evidence most people to be put on death row were identified

DNA evidence is thought to be the greatest tool to determine conviction status of suspects in criminal cases. However, since its use in. issues have arisen between individuals’ understanding of the committed crime and the accurate results of evidence and how this effects a suspect’s final conviction status. As a result, researchers of this article conducted three studies to determine whether scientific forensic evidence is being mistreated by jurors in criminal court case decisions.

Except in the case of identical twins, the probability that two people have the same genetic code at all thirteen core loci is less than one in one trillion (Crest, 2005). Investigators compare these genetic fingerprints with profiles stored in databases of previous offenders, and if they find a match, it proves that the person was at the crime scene. 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 (Silverstein, 1996). Because DNA is so durable, investigators can reopen old cases to reexamine evidence.

DNA is commonly used in the modern legal system to release the innocent or imprison the guilty. There are two different ways to create DNA evidence through science technology, PCR and gel electrophoresis. Polymerase Chain Reaction, PCR, is used to create thousands to millions of copies of DNA, out of a small piece of DNA, this piece is used to make a DNA profile. Doing this makes it easier to test the DNA. PCR is used to find if a gene has pathogens. They are an infectious agent that creates illness or disease and it’s commonly a virus, parasite or bacteria. (1) Gel electrophoresis is the technique used to separate molecules from DNA, RNA or proteins, based on the size or electric charge. It can be used in DNA fingerprinting, the findings and purification of nucleic acids and proteins. Gel electrophoresis can be used to find pathogens that can be found in blood, tissues or sources like food. (2) These are some of the methods that are used in court and police cases to discover DNA.

Forensic science more than often deals with DNA fingerprinting being used as a technique to identify the offender of a crime in a particular case. The DNA fingerprint maybe RFLP, VNTR or STR. RFLP stands for Restriction Length Fragment Polymorphism. VNTR stands for Variable Number of Tandem Repeats. STR stands for Short Tandem Repeats. RFLP was the first DNA fingerprinting method. STR is currently the most popular fingerprinting method. These DNA fingerprinting techniques require restriction enzymes that are obtained from the bacteria, which are used to cut the DNA into smaller fragments at different loci. We also require agarose gel obtained from seaweed and nylon membrane or sheet. Electric current is required so that it can be passed on

Polymerase chain reaction, also known as PCR, is a technique to make multiple copies of a specific DNA region. PCR relies on a thermostable DNA polymerase and requires DNA primers for the specific regions of DNA that is being used. The main goal of PCR is to make enough of the specific DNA, in that region, that can be analyzed for many different reasons. For example, having enough of the DNA amount for forensic scientist would help them match crime scene DNA to the actual suspect.