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An essay on forensic science
An essay on forensic science
An essay on forensic science
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Picture this: you walk into a crime scene and the first thing you see is blood. It is all over the walls, the floor, and even the ceiling. Now any other person would probably not know the information that this evidence holds, but those that have studied blood, how it works, bloodstain patterns, and what they all mean, have an abundance of evidence to examine. Just from looking at the bloodstain patterns, they can discover many things about the crime and how it occurred.
There are five main categories of bloodstains: passive, impact spatter, transfer, other, and latent. Many of these categories also have sub-categories.
Passive stains are influenced by gravity. Passive stains include drips, splashes, flows, and pools. Drips, or drops, can show how far the blood fell from the source. Depending on the size and shape of the drip, the distance and angle the blood fell from can be determined. Also, if the suspect or victim moves throughout the crime scene and leaves a drip trail pattern, their movements can be established. Splashes come from blood dripping into blood. Splashes can lead to flows. Flows are created when accumulated blood flows from one area to another, being pulled by gravity. The flow direction shows movement from the blood source. If the flow is interrupted, this interruption can show the time that passed between the flow and its interruption. Pools can result from flows. A pool occurs when blood collects on a flat surface. If the blood source is on an absorbent surface, the blood will be absorbed and will spread out and create a larger pattern than the original pool.
Impact spatter stains come from the impact between an object and the blood source. Impact spatter can be separated into three classifications, low-veloc...
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...preting bloodstain patterns. Retrieved from http://www.crimescene-forensics.com/Crime_Scene_Forensics/Bloodstains.html
Houck, M. M., Crispino, F., & McAdam, T. (2012). The science of crime scenes. (pp. 323-329). Academic Press.
Minnesota BCA. (2013). Luminol (blood). Retrieved from https://dps.mn.gov/divisions/bca/bca divisions/forensic-science/Pages/forensic-programs-crime-scene-luminol.aspx
Saferstein, R. (2011). Criminalistics: An introduction to forensic sciences. (10th ed., pp. 301 307, 309-313). Upper Saddle River, NJ: Pearson Education, Inc.
Schiro, G. (n.d.). Collection and preservation of blood evidence from crime scenes. Retrieved from http://www.crime-scene-investigator.net/blood.html
Young, T., & Ortmeier, P. J. (2011). Crime scene investigation: A forensic technician's field manual. (pp. 293-302, 305-314). Upper Saddle River, NJ: Pearson Education, Inc.
In order to reconstruct a crime scene, analysis must classify the bloodstain spatter, and there are many way to classify blood stain patterns: bloodstain spatter by velocity and bloodstain through taxonomy. In the classification of the bloodstain spatter by velocity, there are three basic categories of stain groups...
There are different types of bloodstain patterns that give a sense of what happened at the scene. The idea is to get a sort of background story from the random blood distribution. The different types of blood can tell us the method an assailant used such as passive blood stains. These stains are made from the drops off a weapon due to gravity. For instance, if an attacker w...
Fulero, S. M., & Wrightsman, L. S. (2009). Forensic psychology. (3rd ed.). Belmont: Wadsworth, Cengage Learning.
Bloodstain Pattern Analysis is a forensic discipline which, among others, the position of victims can be determined at crime scenes on which blood has been shed. To determine where the blood source was, investigators use a straight-line approximation for the trajectory, ignoring effects of gravity, drag and overestimating the height of the source. We determined how accurately the location of the origin can be estimated when including gravity and drag into the trajectory reconstruction. We created eight bloodstain patterns at one meter distance from the wall. The origin’s location was determined for each pattern with: the straight-line approximation, the method includes gravity, and the method we use includes both gravity and drag. The latter
In case if the firearm is involved, we can approach it as both movable and non-movable object. At the initial stage it can be processed with a super glue fuming and later packed into the paper envelope for the further analysis. In case of the blood stains on it we can go back to the initial stage for the swabbing procedure.
Lyman, D. Michael; Criminal Investigation, The Art and Science; 3rd edition, 2002 Prentice Hall. Pgs. 188-200.
Dutelle, Aric W. An Introduction to Crime Scene Investigation. Sudbury, MA: Jones and Bartlett, 2011. Print.
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...
Review, PubMed PMID: 19543886. Saferstein, R. (2011). Criminalistics: An introduction to forensic science (10th Ed.). Upper Saddle River, NJ: Pearson Education, Inc.
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
Gaensslen, R. E., Harris, H A., & Lee, H. (2008). Introduction to Forensic Science and Criminalistics. New York, NY: The McGraw-Hill Companies, Inc. .