Deoxyribonucleic acid (DNA) is the hereditary material in humans. It is contained in the nucleus of nearly every cell in the human body and is unique to all individuals except in cases of identical twins. Thus, DNA can be used to identify suspects in forensic casework. DNA can be left behind at forensic crime scenes in a variety of ways. Common sources of human DNA at crime scenes include: saliva, blood, semen, skin, and hair follicles. Saliva samples can provide high-quality and high-quantity DNA, but they do have some special issues associated with them (Nemoda, et al., 2011). Saliva samples contain many different substances that could actively degrade the sample. For example, saliva naturally contains microbes that could contaminate the sample, making it seem like there is more suspect DNA present than there actually is (Nemoda, et al., 2011). Also, saliva fluids originate from multiple glands that secrete at different rates in different people, so some samples may contain less DNA than others (Nemoda, et al., 2011). The DNA evidence acquired at crime scenes is analyzed using Forensic DNA Profiling.
Forensic DNA Profiling is an important tool in forensic science for human identification and paternity testing. Profiling utilizes short tandem repeat sequences (STRs) or variable number tandem repeat sequences (VNTRs) for individualization. STRs are short regions of DNA that are repeated numerous times and can vary in number of copies between individuals (figure 1). VNTR and
This paper explores deoxyribonucleic acid (DNA) collection and its relationship to solving crimes. The collection of DNA is one of the most important steps in identifying a suspect in a crime. DNA evidence can either convict or exonerate an individual of a crime. Furthermore, the accuracy of forensic identification of evidence has the possibility of leaving biased effects on a juror (Carrell, Krauss, Liberman, Miethe, 2008). This paper examines Carrells et al’s research along with three other research articles to review how DNA is collected, the effects that is has on a juror and the pros and cons of DNA collection in the Forensic Science and Criminal Justice community.
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
Deoxyribonucleic acid, or DNA as it is most commonly known, is a strand of molecules found within the cell nucleus of all living things. It is called a “genetic fingerprint” because each is different to the other and everyone, apart from identical twins, have
forensic identification technique today1. It is the case of analyzing and profiling a DNA sample
DNA testing is a critical and accurate tool in linking accused and even convicted criminals for crimes, and should be widely used to assess guilt or innocence before jail sentences are imposed. It was started up by scientists Francis C. Crick and James D, Watson in 1953 as they had described the uses, structures and purpose of the DNA “deoxyribonucleic acid” genetic fingerprint that contains organism information about an individual (testing
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.
Deoxyribonucleic acid (DNA) has been used to analyze and prove innocence or guilt of suspects of crimes with great accuracy. DNA is part of everyday life. It is the heredity material in humans and almost all other organisms. While being part of an investigation. DNA has helped to solve crimes. There is a couple ways that DNA left behind can be tested to solve a crime. Either if the suspect has been caught and or had his or her DNA tested, or if he or she has left behind any biological evidence. Which then needs to be tested to see if it matches the DNA found in the crime scene to his or hers DNA. The result to this comparison may help establish if the suspect committed the crime.
DNA evidence is extremely helpful in criminal trials not only because it can determine the guilt of a suspect, but also because it can keep innocent people from going to jail. The suspect must leave a sample of their DNA at the crime scene in order for testing to occur, but DNA can be found in the form of many things such as semen, blood, hair, saliva, or skin scrapings. According to Newsweek, "thousands of people have been convicted by DNA's nearly miraculous ability to search out suspects across space and time… hundreds of innocent people have also been freed, often after years behind bars, sometimes just short of the death chamber" (Adler ). Though some may think it is a waste of time to go
With regard to the US, where social science and STS research have, focused less on forensic databases and more on the production of expertise and evidence in court, Jay Aronson provided a historical account of the early practices, the scientific and legal controversies, and the ultimately successful acceptance of forensic DNA evidence in court in 2007. Another particularity of social science and STS research in this domain is that it has so far mostly concentrated its “high end” forensic technologies, namely those which received a lot of public attention because they were new, because stakeholders in the criminal justice system struggled to determine the parameters of scientific reliability and admissibility, or because they were prominently featured in the media. While the use of DNA analysis for police investigations and forensic casework dates back to the late 1980s, the second half of the 1990s marked the beginning of the quest to render DNA profiles systematically and routinely searchable and minable by setting up centralized DNA databases in many countries around the world. A DNA molecule is a long, twisting chain known as a double helix. DNA looks pretty complex, but it's really made of only four nucleotides: Adenine, Cytosine, Guanine, and Thymine. These nucleotides exist as base pairs that link together like a ladder. Adenine and Thymine always bond together as a pair, and Cytosine and Guanine bond together as a pair.
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).
Teeth and other bones are the only sources of DNA available for human identification. Teeth are good source of both nuclear and mitochondrial DNA and have been successfully used in the forensic identification of human skeletal remains. The unique composition of teeth and their location in the jawbone provides an additional protection to DNA as compared to other bones thus making them a good source of DNA in many different cases. Also, postmortem changes in the structure and composition of teeth, and the location of DNA within them are poorly understood. The tooth morphology with respect to DNA content and the preservation and the postmortem changes will affect the recovery of DNA from teeth.
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.
Recent advancements in DNA technology have improved law enforcement’s ability to use DNA to solve old cases. Original forensic applications of DNA analysis were developed using a technology called restriction fragment length polymorphism (RFLP). Although very old cases (more than 10 years) may not have had RFLP analysis done, this kind of DNA testing may have been attempted on more recent unsolved cases. However, because RFLP analysis required a relatively large quantity of DNA, testing may not have been successful. Similarly, biological evidence deemed insufficient in size for testing may not have been previously submitted for testing. Also, if a biological sample was degraded by environmental factors such as dirt or mold, RFLP analysis may have been unsuccessful at yielding a result (Turman).
DNA is deoxyribonucleic acid, which is found in almost all living things. DNA serves as a code for the creation and maintenance of new cells within an organism. Within humans, it is found in almost every cell. Although most of our DNA is found within the nucleus of our cells as nuclear DNA, a very small amount of our DNA is also found within the mitochondria as mitochondrial DNA. Because mitochondrial DNA is generally not used for solving crimes, for the purpose of this paper it will be disregarded.