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Forensic analysis methods essay
Forensic analysis methods essay
Forensic analysis methods essay
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The ability to determine source of a blood is important to serval fields of science, especially in forensic science (1, 2). Determining the origin of a bloodstain can be beneficial in investigations for wildlife crimes, animal cruelty cases, hit-and-run cases, and other cases as well (1, 2). It can be especially important in hit-and-run cases, because an individual may deny that they were in a vehicular accident where a human was hit (1). They even may lie by telling an investigator that they hit animal to account for the bloodstain and damage to their vehicle (1). As a result, it would be important to link evidence, a crime scene, and/or suspect together.
Before any determination of a source of a bloodstain, presumptive tests are performed on a stain that indicate if a stain is blood or not (1-3). Presumptive tests use chemical reactions with specific blood components (1-3). These tests are sensitive to components such as iron in hemoglobin (1, 3). As a result, presumptive test is unable to differentiate between possible sources of blood, such as human or animal blood (1, 3). Presumptive tests also
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Confirmatory test that can be used are: the Rapid Stain Identification^TM-Blood test, an enzyme immunoassay, the HemeSelect^TM test, the precipitin test, and various other tests as well (1, 3). But currently, the ability to determine if a bloodstain came for a human or animal source involves extracting nuclear DNA, or mitochondrial DNA from a blood sample (1). As a result, a DNA profiles are produced that have targeted species differentiations (1). These confirmatory tests are reliable, but they are destroy the blood samples, can have a multi-step process, can be time-consuming, and expensive (1, 3). As a result, scientists are researching other possible confirmatory tests that are less expensive, less time-consuming, and non-destructive
Three hundred and thirty-four years later in the future, Carl Landsteiner, a Viennese doctor, performed a very simple experiment with blood in 1901. During his experiment, Landsteiner noticed "clotting in some samples of mixed blood and not others". (Tucker, 10) Landsteiner separated his samples into three groups: A, B, and C, according to how they clotted in his experiment. Today, the blood type C is known as type O blood. When Landsteiner was grouping these blood types, he happened to look over type AB. AB occurs in about 3 percent of the population. Later in 1907, two researchers, Jan Jansky in Czechoslovakia and William Lorenzo Moss in the United
Peschel, O., Kunz, S. N., Rothschild, M. A., & Mützel, E. (2011). Blood stain pattern analysis. Forensic science, medicine, and pathology, 7(3), 257-270. http://link.springer.com/article/10.1007/s12024-010-9198-1
A common tool that forensic units use is the ultra violet or UV light. Ultra violet light can detect different areas that contain blood that might not be able to be seen in other conditions. Another common tool is the blood reagent test that forensics use on scene. These tests determine if the blood is human or animal. Renee Blake - "The 'Renee Blake'" There are different types of bloodstain patterns that give a sense of what happened at the scene.
The blood of the unknown person became apparent through comparing the blood type found at the crime scene with the contrasting blood types of the suspects. The blood identified at the crime scene could have possibly belonged to Anna Garcia or Erica Piedmont. This observation was based on the information that the blood type found at the crime scene was type A and these two individuals are the only ones that carry that specific type. In similarity, a microscopic photography was taken of the unknown hair follicle found at the crime scene. Then hair samples were taken from the potential suspects, and the victim. These findings were then compared. This was done by looking at each individuals hair follicles and comparing it with the unknown one. By looking at the similarities and differences in medulla diameter, the discovery of the unknown hair follicle became established that it belonged to Anna Garcia. Further examination resulted in the analyzation of a shoe print found at the crime scene. Shoe patterns and sizes were taken from each suspect, including the victims. They were then identified and compared to the one found at the crime scene. By looking at the distinct pattern, size, and the fact that both shoes were a Columbia brand sneaker it became obvious that the shoe print was extremely similar to Anna’s shoe design. Through this found evidence it became
Crime scenes are known to have many clues left behind. The obvious would be a the body or bodies, clothing, and sometimes even the murder weapon. While these are great way to solve a case there's another kind of evidence; trace evidence. Trace evidence are small pieces of evidence that are laying around a crime scene. There are many types of trace evidence some of them include metal filings, plastic fragments, gunshot residue, glass fragments, feathers, food stains, building materials, lubricants, fingernail scrapings, pollens and spores, cosmetics, chemicals, paper fibers and sawdust, human and animal hairs, plant and vegetable fibers, blood and other body fluids, asphalt or tar, vegetable fats and oils, dusts and other airborne particles, insulation, textile fibers, soot, soils and mineral grains, and explosive residues. Although these are the most common found elements, they are not the only ones. The Trace Evidence Unit is known to examine the largest variety of evidence types and used the biggest range of analytical methods of any unit. materials are compared with standards or knowns samples to determine whether or not they share any common characteristics. In this paper I will discuss the different kinds of trace evidence and how crime scene investigaros use it to solve cases and convict criminal.
The criminal justice system has changed a lot since the good old days of the Wild West when pretty much anything was legal. Criminals were dealt with in any fashion the law enforcement saw fit. The science of catching criminals has evolved since these days. We are better at catching criminals than ever and we owe this advancement to forensic science. The development of forensic science has given us the important techniques of fingerprinting and DNA analysis. We can use these techniques to catch criminals, prove people's innocence, and keep track of inmates after they have been paroled. There are many different ways of solving crimes using forensic evidence. One of these ways is using blood spatter analysis; this is where the distribution and pattern of bloodstains is studied to find the nature of the event that caused the blood spatter. Many things go into the determination of the cause including: the effects of various types of physical forces on blood, the interaction between blood and the surfaces on which it falls, the location of the person shedding the blood, the location and actions of the assailant, and the movement of them both during the incident. Another common type of forensic evidence is trace evidence. This is commonly recovered from any number of items at a crime scene. These items can include carpet fibers, clothing fibers, or hair found in or around the crime scene. Hairs recovered from crime scenes can be used as an important source of DNA. Examination of material recovered from a victim's or suspect's clothing can allow association to be made between the victim and other people, places, or things involved in the investigation. DNA analysis is the most important part of forensic science. DNA evidence can come in many forms at the crime scene. Some of these forms include hair; bodily fluids recovered at the crime scene or on the victim's body, skin under the victim's fingernails, blood, and many others. This DNA can be the basis of someone's guilt or innocence; it has decided many cases in the twentieth century. As the times continue to change and the criminals get smarter we will always need to find new ways to catch them. Forensic science is the most advanced method yet, but is only the beginning. As the field of science grows so will the abilities of the
In today’s time, modern Crime Scene Investigation has increased rapidly. From throughout the late 1900’s and in the early 2000’s (Taylor 1). For all of the evidence that they find, a solid foundation has formed over the thousands of years of Crime Scene
In here I will clarify each potential evidences of the crime and explain of the application of the identified forensic procedure to the facts of the case. One of the perpetrators cuts his hand when trying to drag of the witness in the crime scene. Thus, in this case blood stains would be the one of the potential evidence. The precipitin test might be applied to bloodstains in a numerous ways. It conduct...
...he case of forensics. You can go beyond the normal reality of blood spatter (?.. how does or where did blood spatter come into play here). The species of a set of bones can be determined through forensics anthropology. The sex of a skeleton. The age of a person and by studying the bones you can find a person’s age. Forensics Anthropology, (2014)
In Blood In Blood Out is a drama directed by Taylor Hackford, and starring Damian Chapa (Miklo), Benjamin Bratt (Paco), and Jesse Borrego (Cruz), produced by Hollywood Pictures. The film was based off everyday life in East Los Angeles, from the 1970’s through the 1980’s. Damian Chapa stars as Miklo in the film, a Mexican-American who wanted to be accepted, not by his skin but for the Mexican within him. Benjamin Bratt (Paco) was the older cousin of Miklo, who learned his lesson throughout the movie and changed his ways. Jesse Borrego (Cruz) is the step-brother of Paco who was a talent artist, who ended up turning to drugs because of back problems caused by a rival gang incident.
Blood stains are one type of evidence that can be found at a crime scene. Blood that is still in the liquid form should be picked up on a gauze pad. Once the blood is dried thoroughly it should be refrigerated and sent to the Laboratory (Andrus et al., n.d., para. 1). If the blood stain is found dried on clothing, the officer should wrap the piece of clothing in clean paper and place it in a sealed and labeled container. An object with dried blood stains needs to be sent to the Laboratory if it is small enough. If the object is too large to send, then using a clean knife the stain needs to be scraped onto a clean piece of paper, which then can be folded and placed in an envelope (Andrus et al., n.d., para. 2). When collecting autopsy blood samples, the officer should request that the pathologist obtain the sample directly from the heart and place it in a yellow or purple stoppered vacutainer. If the victim is still alive but in serious need of a blood transfusion, then the pre-transfusion blood sample needs to be obtained promptly before the hospital discards it (Andrus et al., n.d., para. 4). It is important for the Laboratory to receive all blood samples within 48 ho...
As far back as 1832, James Marsh was the first to use forensics at trial to give evidence as a chemist in 1832. Since that time forensic science and evidence has come a long way in various ways and technology to help in determine if the suspect is guilt or not, through such things as DNA testing, blood, and fingerprints. The first forensic police crime lab was created in 1910. The contributions of Dr. Edmond Locard, a French scientist and criminologist, proposed that “everything leaves a trace”. This principle is still valid today as it was so many years ago. No matter how small, the specialized trained technicians and investigators can take these methods and go to a crime scene to get evidence. “Forensic science is the application of sciences such as physics, chemistry, biology, computer science and engineering to matters of law.” (Office of Justice, 2017) These different sciences can help achieve and assist in solving a case. Forensic science has also the ability to prove that a crime was committed, it can find the elements of the crime, it can help place the suspect at the scene and whether the suspect had any contact with the victim. However, in the last several years the techniques and with the use of technology the evidence that forensic science uncovers can also exonerate an innocent individual who has been falsely accused of the
Coughlin, S. S. (2002). Future challenges for research on diagnostic tests: genetic tests and disease prevention. Journal of Epidemiology & Community Health, 56(5), 335-336. doi:10.1136/jech.56.5.335
First I will introduce the amounts of animals that are being used in these tests and those tests that they are being used for.
scientific method for things such as DNA samples from hair and body fluids, fingerprint analyses and