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Forensic Science Lecture Notes.pdf

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CHY 183
Monica Sauer

Forensic Science • Study Guide By: Candice Bentham Video I • Lecture I By: Candice Bentham How was the Locard's Exchange Principle illustrated in the video we watched in class? Within the Case the suspec t manage to remain anonymous by taking any type of trace evidence on the victims. However with the eyewitness account of her experience with the suspect they forensic evidence began to share similarities among the group of victims. According to Locard’s T heory, once a person comes into contact with an object or another person a cross transfer of physical evidence occurs. In the Case with the suspect crime science investigators found bacteria on the victim body that shared similar traits to bacteria that wa s found on the floor of the suspect’s car. Concluding that the chances of these two bacteria begin the same was very low. The transfer of bacteria from the suspects’ car to the dead body proves that Locard’s theory is in fact plausible and can lead to find ing the guilty suspect. • Murderer: Roger Kibbe Evidence: • Blue Carpet fibers • Pet hair • Fibers on victim’s pantyhose • Rope white nylon – 32 threads per cord – red paint particles on the rope - 6 microns Forensic Science • Lecture I By: Candice Bentham Forensic Science • Definition. The application of science to criminal and civil law • The entire concept of forensic science owe its origins to individuals such as Bertillon, Galton, Lattes, Goddard, Osborn, and Locard who developed the principle and techniques needed to identify or compare physical evidence. Initial Scientific Advances • Mathieu Orfila. The father of forensic toxicology, in 1814 Orfila published the first scientific treatise on the detection of poison and their effects on animals . • Morphology. Is the study of the structure of the living organisms? • Alphonse Bertillion. Devised the first scientific system of personal identification in 1879. This system was dubbed Anthropometry, which consisted in taking a series of body measurements as a means of distinguishing one individual from another. • Francis Galton- Conducted the first definitive study of fingerprints and their classification. His work went on to describe the basic principle that forms the present system of identification by fingerprints. 20 thCentury Breakthroughs • Leone Lattes. Developed a procedure to determine blood type from dried bloodstains. • Albert Osborn. Was the first person to develop the fundamental principle of document examination • Edmond Locard. Was a Frenchman w hom demonstrated that when a criminal comes in contact with an object or person a cross transfer of evidence occurs. o He strongly believed that every criminal can be connected to a crime by dust particles carried from the crime scene. • The most significant modern advances of in forensic science has been the th st discovery and refinement of DNA typing in the late 20 and early 21 centuries. • Sir Alec Jeffrey. Developed the first DNA profiling test in 1984 • Another recent development in forensic is the establishm ent of computerized database on physical evidence such as fingerprints, marking on bullets and shell casing and DNA. Crime Laboratories • The steady advances in forensic science during the 20 thcentury led to the establishments of the first facilities speci fically dedicated to forensic analysis of criminal evidence. o The supreme court decision in the late 60s responsible for police placing greater emphasis on scientifically evaluated evidence o Crime lab inundated with drug specimens due to accelerated drug a buse o The advent of DNA profiling • The technical support provided by the crime lab can be assigned by 5 basic services o Physical science unit. Incorporates the principle of chemistry, physics, and geology to identify and compare physical evidence. o Biology Unit. Applies the knowledge of biological science in order to investigate blood samples, body fluid, hair, and fiber samples. o Firearms Unit. Investigates discharged bullets cart o Document examination Unit. Studies the handwriting and typewriting on questioned documents. o Photography unit. A complete lab examines and records physical evidence. It may require some high level photographic techniques. Optional Services provided by full crime labs • Toxicology Unit examines body fluids and organs for the presence of drugs and poisons. • Latent Fingerprint Unit processes and examines evidence for latent fingerprints. • Polygraph Unit conducts polygraph or lie detector tests. • Voiceprint Analysis Unit attempts to tie a recorded voice to a particular suspect. • Evidence-Collection Unit dispatches specially trained personnel to the crime scene to collect and preserve physical evidence. The Scientific Method • Formulate a question worthy of investigation. • Formulate a reasonable hypothesis to answer the question. • Test the hypothesis through experimentation. • Upon validation of the hypothesis, it becomes suitable as scientific evidence. Skills of a forensic scientist • A forensic scientist must be skilled in applying the principles and techniques of the physical and natural sciences to the analysis of the many types of evidence that may be recovered during a criminal investigation. • A forensic scientist may also provide expert court testimony. • An expert witness is an individual whom the court determines possesses knowledge relevant to the trial that is not expected of the average person. • The expert witness is called on to evaluate evidence based on specialized training and experience that the court lacks the expertise to do. • The expert will then express an opinion as to the signi ficance of the findings. • Forensic scientists also participate in training law enforcement personnel in the proper recognition, collection, and preservation of physical evidence. Analyzing Physical Evidence • The three major avenues available to police for assistance in solving a crime are; o Confession o Eyewitness or victims accounts of the accident o Physical evidence • Science derives from adhering to strict guidelines that ensures careful and systematic collection, organization, and analysis of information - a process called scientific method • This method provided a safety net to ensure that the outcome of an investigation is not tainted by human emotion or compromised by distorting, belittling or ignoring contrary evidence The Frye Standard • The Frye v. United States decision set guidelines for determining the admissibility of scientific evidence into the courtroom. • To meet the Frye standard, the evidence in question must be “generally accepted” by the scientific community. Daubert Criteria For Admissi bility • Whether the scientific technique or theory can be tested. • Whether the technique has been subject to peer review and publication. • The techniques potential rate of error. • Existence and maintenance of standards . • Whether the scientific theory or metho d has attracted widespread acceptance within a relevant scientific community. Special Forensic Science Services • A number of special forensic science services are available to the law enforcement community to augment the services of the crime laboratory. • These services include forensic pathology, forensic anthropology, forensic entomology, forensic psychiatry, forensic odontology, computer science, and forensic engineering. • Forensic Psychiatry is an area in which the relationship between human behavior and legal proceedings is examined. • Forensic Odontology involves using teeth to provide information about the identification of victims when a body is left in an unrecognizable state. Also investigates bite marks. • Forensic Engineering is concerned with fai lure analysis, accident reconstruction, and causes and origins of fires or explosions. • Forensic Computer Science involves the examination of digital evidence. Forensic Science • Lecture II By: Candice Bentham Review from Lecture I The Scientific Method • Figure out who is the murderer • Formulate a Hypothesis • Test the hypothesis • Using the hypothesis to become a expert witness Skills of a Forensic Scientist • A forensic scientist must be skilled with many types of evidence that ma y be recovered during the investigation • A forensic scientist may also contribute to the trial as a expert witness • Opinion based on there credentials Daubert Criteria for admissibility • Every thing must be reproducible • There needs to be standards when te sting evidence • It needs to be accepted by the relevant to an expert scientist (someone who specializes in that area of study) Chapter II • The Crime Scene Physical Evidence • As automobiles run on gas, crime labs run on physical evidence • The evidence must be documented • The forensic science begins at the crime scene The First Steps • The first responder is responsible for securing the crime scene • The purpose of securing the crime scene is to reduce the chances of adding new evidence, or disturbance in t he crime scene • The first step must be to take care of the injured victims • The first CSI assess the scene, by conducting a preliminary exam and recoding the critical piece to process • Recording Methods • Sketching out the crime scene, taking pictures, and wr iting notes are three key methods of recoding the scene Photograph • Shows the evidence under unaltered conditions • Shows images through a close up view Sketches • Once the photos are taken the crime scene the investigator will sketch the scene • It depicts physical evident are found, a blue print of the crime scene, scale of the room - What the physical evidence is - Where you found it - What did the investigator do with it • Finish sketches. A precise rendering of crime scene usually to scale. This type is not normally competed at the crime scene Notes • Taking notes are important guide to where exactly the evidence was found • Notes is information for refreshing one’s mind before the case reaches trail • Investigators have a limited amount of time to record The Preliminary Exam • The lead investigator will stat the processing in the crime scene • There are different search patterns selected will normally depend on the size • If there is a large area the best method to use is strip line or grid method • For more circular area a spiral is best. Why start from the outside? The reason is to collect all the evidence as you go along The Search • If the object has trace evidence it is best to take it to the lab for further analysis • By taking small amounts of these trace eviden ce Beyond the Crime Scene • The search for the physical evidence must extend beyond the crime scene • The medical examiner or coroner will carefully examine the victim to establish a cause and a manner of death • Is their any evidence to the tissue, interna l bleeding, to determine the cause of death Packaging • Each different item or similar items collect at different locations must be placed in separate containers • Hair can be placed in small containers that keeps the evidence safe Chain of Custody • A list of all person who come into contact with evidence that is related to the case • Continuity of Possession. Must be established whenever the evidence is presented in the court as an exhibit • Every person that comes in contact with the examined evidence must be accounted for. Obtaining Reference Samples • Are standard that are from the scene; ie possible suspects, witnesses • There should be samples that can be compared from the scene and from the manufactured material or from a person Special Forensic Scien ce Services • Forensic Pathology involves the investigation of unnatural, unexplained, or violent deaths • The forensic pathologist may conduct an autopsy, which is the medial dissection and examination of a body in order to determine the cause of death Stages of Death • Rigor Mortis. Results in the shortening of muscle tissue and the stiffening of the body parts in the position at death – occurs within the first 24hrs and disappears within 36hrs. • Livor Mortis. Results in the settling of blood in areas of th e body closest to the ground – begins immediately on death and continues up to 12hrs • Algor Mortis. Results in the loss of heat by the body - begins an hour after death and the by loses heat by 1 -1.5 degree F per hour. Forensic Psychiatry. • Is a specialized area that examines the relationship between the human behavior and the legal proceedings • In terms of civil cases it can determine whether a person is competent to make decisions about preparing a will or refusing medical treatment. • Also determining if a defendant are competent to stand trial Forensic Odontology • Practitioner help identity victim based on dental evidence when the body is left in a unrecognizable state. Forensic Engineering • Are concerned with the failure analysis accident reconstructio n and causes and origins of fires and explosions • Forensic computer and digital analysis • This is a new and fast growing field that involves identifying, collecting, and examining information derived from computers and other digital devices. • Law enforcements aspect of this work normally involves recovering deleted or overwritten data from computer’s hard drive and tracking hacking activities within a compromising system. Forensic Anthropology • The concern with the identification and examination of human skel etal remains. • Bones can tell age, and for babies (skull formation), gender (male vs. female) Forensic Entomology • The study of insect and their reaction to a criminal investigation used to estimate the time of death • Blow Flies, are the first at the scene . Forensic Science • Lecture III By: Candice Bentham Chapter III • Physical Evidence Physical Evidence • Almost anything can be physical evidence • The purpose of recognizing physical evidence is so that it can be collected and analyzed • It is difficult to determine whether evidence is valid or not unless it is collected and weighted by the jury in the case Types of Physical Evidence • Blood, semen and saliva • Plastic, Rubber, and other • Documents polymers • Drugs • Wood and other vegetative • Fibers matter • Fingerprints • Vehicle lights • Powder Residues • Glass • Petroleum Products • Hair • Paint • Impressions • Plastic bags • Organ and physiological fluids • Soil and Minerals • Firearms and ammunition • Tool marks • Explosive Purpose of examining physical evidence • The propose of determining of the physical or chemical identity of a substance with as near absolute certainly as existing analytical techniques will permit Identification • The object of identification is to determine the physical or chemical identity with as near absolute certainty as existing analytical tech will permit • Fingerprints and DNA are good for identification Comparison analysis • Subjects that are reference specimens to the specimen found at the crime scene. The ultimate purpose to determine whethe r or not they have a common origin • What needs to be analysis first, a combination of selected properties are chosen from the suspect and standard for comparison • First, combinations of select properties are chosen from the suspect and the standard reference specimen for comparison • Second, once the examination has been completed the forensic scientist must be prepared to render a conclusion with respect to the origins. Role of Probability • To comprehend the evidential values of a comparison one must apprec iate the roles that probability has in ascertaining the origins of two or more specimens • Simply defined probability is the frequency of occurrence of an event Classifying Characteristics • Individual Characteristics o Evidence that can be associated to a comm on source with an extremely high degree of probability is said to possess individual characteristics o It all cases it is not possible to state with math exactness the probability that the specimens are of common origin o It can only be concluded that this pro bability is so high as to defy math cal or human comprehensions Examples ! The matching ridges characteristics of two fingerprints ! The comparison of random striation marking on bullet or tool marks ! The comparisons or irregular and random wear pattern in tire or footwear impressions
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