The Importance Of Physical Evidence

Physical evidence is anything that can establish a crime has occurred and anything that links the crime to a criminal. Three examples of physical evidence are fibers, weapons, and hair.

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

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

One of the most important purposes of physical evidence is to establish the identity of a suspect or victim. Some of the most valuable clues at a crime scene are fingerprints. "Processing a crime scene" is a long, tedious process that involves focused documentation of the conditions at the scene and the collection of any physical evidence that could possibly shed light on what happened and point to who did it.

However, back in the 1980s, detailed studies were done to try to accomplish this task. One specific comprehensive study was done in 1984 by Peterson et al. In this study, the analysts found that physical evidence was discovered in only about twenty to thirty percent of serious crimes (Peterson, 2013). When each of the crimes were studied separately, however, they found that only crimes such as homicide, drug, or rape resulted in a large chance of physical evidence being found at the crime (Peterson, 2013). Cases such as attempted murder, burglaries, and robberies yielded lower chances of the retrieval of physical evidence from the crime (Peterson, 2013). When considering all of these possible crimes, the most commonly collected evidence were controlled substances, and then in lesser amounts, there was other physical evidence such as blood, hair, firearms, and fingerprints (Peterson, 2013).

Forensic evidence has been shown to be reliable due to many factors of evidence such as DNA, blood, fingerprints, etc.; however, many cases have shown that

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

Advances in DNA technology has expanded greatly in the world of forensic science. In the past a vast number of crime scene evidence was not considered for analysis is now being tested. Trace DNA is more effective in this century when convicting a criminal than it was 20-30 years ago. Due to the consist improvement of DNA technology forensic scientist are able to put away criminals the correct way.

This paper will tell some basic ways of collecting the evidence and how to preserve the evidence without contamination. It also tells how to remove a bullet from surroundings as well as a deceased body.

Behind every court case there’s a train of forensic science evidence and research. Forensic science is the application of scientific principles of criminal justice. In many court cases a forensic scientists is the one on the scene collecting finger prints, photos, blood samples and other evidence. Unfortunately one of the controversial issues in the forensic world is the evidence and its lack of verification of its reliability. In the field of forensics there are issues in finding proof in generating conclusion, fundamental knowledge to solve problems, and the whole false memory defense in the court. These issues can be solved in many ways like extensive research, preparation and training. These issues

Physical evidence/scientific examinations is the evidence found at the scene of the crime. This can include clothing, blood, fingerprints, weapons and much more. An example of physical evidence could be any listed above but also a bloody knife or a casing from a bullet.

The book gives a general overview of the field of forensic science. The sections of the book include “The Scene of the Crime; Working the Scene--The Evidence; Working the Scene of the Body Human;

Forensic science involves the use of science to solve criminal and civil crimes but mostly lies on the side of criminal investigations. It makes it possible to identify the criminals based on the DNA traces they leave behind. It involves analyses of blood, DNA and other evidences and later on uses the findings as evidence in the court of law. It helps in solving the various crimes in the world and this has been the greatest contributor to the growth of the sector. Cases that were previously considered impossible due to lack of evidenced tracing to the victim can now be solved using forensic science evidences. The essay aims at analyzing the different aspects of forensic science that are used in the process of solving criminal activities. It will also look at the different cases that forensic science was used to solve crimes in a court of law.

Today, more than ever, the quality of evidence in criminal cases is scrutinized because of contamination. Contamination is the introduction of something that physically corrupts a substance at a crime scene that was not previously there; it comes in many forms and most often times comes from the humans who investigate a crime scene. It is imperative that prevention of cross-contamination is implemented when gathering evidence. Several of the more sensitive forensic techniques such as trace analysis, bloodspatter interpretation, and DNA comparison are not being used to their fullest potential. Items of physical crime scene evidence are not always visible to the naked eye and may be easily overlooked so deliberate and methodical approach to collection and preservation of evidence is essential. Prosecutors have lost cases due to crime scene contamination; this could be prevented by simple and productive behaviors. The U.S. Supreme Court, in a leading case on physical evidence, stated: