Chapter 3: Physical Evidence “You can learn a lot by just watching.” —Yogi Berra, former New York Yankees catcher and sage Kendall/Hunt

Please Do Now What is evidence? State 5 examples. Chapter 2 Kendall/Hunt

Locard’s Exchange Principle Chapter 2 Locard’s Exchange Principle Edmond Locard (1877-1966) “Locard's Exchange Principle” states that whenever two objects come into contact there is a transference of material between them. Kendall/Hunt

Types of Evidence Two general types: Chapter 2 Types of Evidence Two general types: Testimonial—a statement made under oath; also known as direct evidence or Prima Facie evidence Physical—any object or material that is relevant in a crime; also known as indirect evidence. Examples are hair, fiber, fingerprints, documents, blood, soil, drugs, tool marks, impressions, glass. Note: This chapter will focus on physical evidence Kendall/Hunt

Reliability of Eyewitness Chapter 2 Reliability of Eyewitness Factors: Nature of the offense and the situation in which the crime is observed Characteristics of the witness Manner in which the information is retrieved Additional factors: Witness’s prior relationship with the accused Length of time between the offense and the identification Any prior identification or failure to identify the defendant Any prior identification of a person other than the defendant by the eyewitness Kendall/Hunt

Chapter 2 Eyewitness A police composite may be developed from the witness testimony by a computer program or forensic artist. “Perception is reality.” As a result of the influences in eyewitness memory, physical evidence becomes critical. Faces—a composite program by InterQuest Kendall/Hunt

Value of Physical Evidence Chapter 2 Value of Physical Evidence Generally more reliable than testimonial Can prove that a crime has been committed Can corroborate or refute testimony Can link a suspect with a victim or with a crime scene Can establish the identity of persons associated with a crime Can allow reconstruction of events of a crime Kendall/Hunt

Chapter 2 Physical Evidence It would be impossible to list all the objects that could conceivably be of importance to a crime. Almost anything can be Physical Evidence. Although you cannot rely on a list of categories, it is useful to discuss some of the most common types of physical evidence. The purpose of recognizing physical evidence is so that it can be collected and analyzed. It is difficult to ascertain the weight a given piece of evidence will have in a case as ultimately the weight will be decided by a jury. Kendall/Hunt

Common Types of Physical Evidence Chapter 2 Common Types of Physical Evidence Blood, semen, and saliva Documents Drugs Explosives Fibers Fingerprints Firearms and ammunition Glass Hair Impressions Organs and physiological fluids Paint Petroleum products Plastic bags Plastic, rubber, and other polymers Powder residues Serial numbers Soil and minerals Tool marks Vehicle lights Wood and other vegetative matter Kendall/Hunt

Physical Evidence Blood, semen and saliva Documents Chapter 2 Kendall/Hunt

Physical Evidence Drugs Explosives Chapter 2 Physical Evidence Drugs Explosives An arrangement of psychoactive drugs including (counter-clockwise from top left): cocaine, crack, methylphenidate (Ritalin), ephedrine, MDMA (Ecstasy - lavender pill with smile), mescaline (green dried cactus flesh), LSD (2x2 blotter in tiny baggie), psilocybin (dried psilocybe cubensis mushroom), Salvia divinorum (10X extract in small baggie), diphenhydramine (Benadryl - pink pill), Amanita muscaria (red dried mushroom cap piece), Tylenol #3 (contains codeine), codeine containing muscle relaxant, pipe tobacco (top), bupropion (Zyban - brownish-purple pill), cannabis (green bud center), hashish (brown rectangle). Kendall/Hunt

Physical Evidence Fibers Fingerprints Silk fibers Chapter 2 Kendall/Hunt

Physical Evidence Firearms and ammunition Glass Refractive index Chapter 2 Physical Evidence Firearms and ammunition Glass Refractive index Kendall/Hunt

Physical Evidence Hair Impressions Dyed human hair Impression foam Chapter 2 Physical Evidence Hair Impressions Dyed human hair Impression foam Hair shaft comparison Kendall/Hunt

Physical Evidence Organs and physiological fluids Paint Chapter 2 Physical Evidence Organs and physiological fluids Paint Car paint layers 300X Kendall/Hunt

Physical Evidence Petroleum products Plastic bags Chapter 2 Kendall/Hunt

Physical Evidence Plastic, rubber and other polymers Powder residues Chapter 2 Physical Evidence Plastic, rubber and other polymers Powder residues Powder residue test Kendall/Hunt

Physical Evidence Serial numbers Soil and minerals Chapter 2 Physical Evidence Serial numbers Soil and minerals Serial number restoration Kendall/Hunt

Physical Evidence Tool marks Vehicle lights Honda Tail lights Chapter 2 Physical Evidence Tool marks Vehicle lights Honda Tail lights Kendall/Hunt

Physical Evidence Wood and other vegetative matter Mixed pollen Chapter 2 Physical Evidence Wood and other vegetative matter Mixed pollen Diatoms Kendall/Hunt

Common Types of Physical Evidence Chapter 2 Blood, semen, and saliva Documents Drugs Explosives Fibers Fingerprints Firearms and ammunition Glass Hair Impressions Organs and physiological fluids Paint Petroleum products Plastic bags Plastic, rubber, and other polymers Powder residues Serial numbers Soil and minerals Tool marks Vehicle lights Wood and other vegetative matter Kendall/Hunt

Using Physical Evidence Chapter 2 Using Physical Evidence As the number of different objects linking an individual to a crime scene increases, so does the likelihood of that individual’s involvement with the crime Also a person may be exonerated or excluded from suspicion if physical evidence collected at a crime scene is found to be different from standard/reference samples collected from that suspect Kendall/Hunt

Why Examine Physical Evidence? Chapter 2 Why Examine Physical Evidence? The examination of physical evidence by a forensic scientist is usually undertaken for identification or comparison purposes. Identification has, as its purpose, the determination of the physical or chemical identity of a substance with as near absolute certainty as existing analytical techniques will permit. A comparison analysis subjects a suspect specimen and a standard/reference specimen to the same tests and examinations for the ultimate purpose of determining whether or not they have a common origin. Kendall/Hunt

Chapter 2 Identification to determine the physical or chemical identity with as near absolute certainty as existing analytical techniques will permit first requires the adoption of testing procedures that give characteristic results for specific standard materials Once these test results have been established, they may be permanently recorded and used repeatedly to prove the identity of suspect materials Second, the number and type of tests needed to identify a substance be sufficient to exclude all other substances Kendall/Hunt

Common Types of Identification Chapter 2 Common Types of Identification The crime lab is often requested to identify: Chemical composition of an illicit drug Gasoline in residues recovered from the debris of a fire, or the nature of explosive residues— for example, dynamite or TNT Blood, semen, hair or wood - including a determination for species origin Kendall/Hunt

Chapter 2 Comparison A comparative analysis has the important role of determining whether or not a suspect specimen and a standard/reference specimen have a common origin. Both the standard/reference and the suspect specimen are subject to the same tests. Kendall/Hunt

Forensic comparison A two step procedure: Chapter 2 Forensic comparison A two step procedure: 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 draw a conclusion about the origins of the specimens Kendall/Hunt

Role of Probability in Forensic Comparison Chapter 2 Role of Probability in Forensic Comparison To comprehend the evidential value of a comparison, one must appreciate the role that probability has in ascertaining the origins of two or more specimens Probability: the frequency of occurrence of an event Easy to establish the probability of flipping a coin Exact probability is impossible to define with many analytical processes Kendall/Hunt

Chapter 2 Probability For example: Blood Factors Frequency A 26% EsD 85% PGM 2+2— 2% What is the probability of someone having all three factors? Using the product rule: 0.26 X 0.85 X 0.02 = 0.00442 which is ONLY 0.442% or 1OO or 1 out of 226 people .442 Kendall/Hunt

Classifying Characteristics Chapter 2 Classifying Characteristics Individual Characteristics Properties of evidence that can be attributed to a common source with an extremely high degree of certainty Class Characteristics Properties of evidence that can only be associated with a group and never with a single source Kendall/Hunt

Individual Characteristics Chapter 2 Individual Characteristics In all cases, it is not possible to state with mathematical exactness the probability that the specimens are of common origin. It can only be concluded that this probability is so high as to defy mathematical calculations or human comprehension. Kendall/Hunt

Evidence Characteristics Chapter 2 Evidence Characteristics Class characteristics—Evidence common to a group of objects or persons Individual characteristics—Evidence can be identified with a particular person or a single source with an extremely high degree of probability Fingerprints Blood DNA Typing Kendall/Hunt

Examples of Individual Characteristics Chapter 2 Examples of Individual Characteristics the matching ridge characteristics of two fingerprints the comparison of random striation markings on bullets or tool marks the comparison of irregular and random wear patterns in tire or footwear impressions the comparison of handwriting characteristics the fitting together of the irregular edges of broken objects in the manner of a jigsaw puzzle matching sequentially made plastic bags by striation marks running across the bags Kendall/Hunt

Class vs Individual Evidence Chapter 2 Class vs Individual Evidence Which examples do you think could be individual evidence? Kendall/Hunt

Class vs Individual Evidence Chapter 2 Class vs Individual Evidence These fibers are class evidence—there are millions like them. The large piece of glass fits to the bottle—it is individual evidence Kendall/Hunt

Class vs Individual Evidence Chapter 2 Class vs Individual Evidence This tape is class evidence—but it could be individual evidence if the striations of the tear match. it is individual evidence— the dental work on the teeth can be used to identify the person Kendall/Hunt

Class vs Individual Evidence Chapter 2 Class vs Individual Evidence This tire track is class evidence, as it can be linked to a class of tire —but it could be individual evidence if there are unique impressions. Kendall/Hunt

Class Characteristics Chapter 2 Class Characteristics Frequently forensic scientists cannot relate physical evidence to a common origin with a high degree of certainty Evidence is said to possess class characteristics when it can be associated only with a group and never with a single source. Again, probability is a determining factor. Nevertheless, the high diversity of class evidence in our environment makes their comparison very significant in the context of a criminal investigation. Kendall/Hunt

Chapter 2 Class Evidence A weaknesses of forensic science is the inability of the examiner to assign exact or even approximate probability values to the comparison of most class physical evidence. For example, what is the probability that a nylon fiber originated from a particular sweater, or that a paint chip came from a suspect car in a hit and run? There are very few statistical data available from which to derive this information, and in a mass-produced world, gathering this kind of data is increasingly elusive. Kendall/Hunt

Chapter 2 Class Evidence One of the primary endeavors of forensic scientists must be to create and update statistical databases for evaluating the significance of class physical evidence. Most items of physical evidence retrieved at crime scenes cannot be linked definitively to a single person or object. The value of class physical evidence lies in its ability to provide corroboration of events with data that are, as nearly as possible, free of human error and bias. Kendall/Hunt

Chapter 2 Class Evidence The chances are low of encountering two indistinguishable items of physical evidence at a crime scene that actually originated from different sources. When one is dealing with more than one type of class evidence, their collective presence may lead to an extremely high certainty that they originated from the same source. Finally, the contribution of physical evidence is ultimately determined in the courtroom. Kendall/Hunt

Chapter 2 Crossing Over Crossing over the line from class to individual does not end the discussions. How many striations are necessary to individualize a mark to a single tool and no other? How many color layers individualize a paint chip to a single car? How many ridge characteristics individualize a fingerprint? How many handwriting characteristics tie a person to a signature? These are all questions that defy simple answers and are the basis of arguments. Kendall/Hunt

Natural vs. Evidential Limits Chapter 2 Natural vs. Evidential Limits There are practical limits to the properties and characteristics the forensic scientist can select for comparison. Modern analytical techniques have become so sophisticated and sensitive that natural variations in objects become almost infinite. Carrying natural variations to the extreme, no two things in this world are alike in every detail. Evidential variations are not the same as natural variations. Distinguishing variations of evidential use from natural variations is not always an easy task. Kendall/Hunt

Forensic Databases The ultimate contribution a criminalist can make is Chapter 2 Forensic Databases The ultimate contribution a criminalist can make is The crime lab is on the forefront of the investigation seeking to identify perpetrators computerized databases link all 50 states and those that link police agencies throughout the world to link a suspect to a crime through comparative analysis Kendall/Hunt

Chapter 2 Forensic Databases Integrated Automated Fingerprint Identification System (IAFIS) a national fingerprint and criminal history system maintained by the FBI 60 million prints on file Kendall/Hunt

Forensic Databases Combined DNA Index System (CODIS) Chapter 2 Forensic Databases Combined DNA Index System (CODIS) enables federal, state, and local crime laboratories to electronically exchange and compare DNA profiles - maintained by the FBI Kendall/Hunt

Chapter 2 Forensic Databases National Integrated Ballistics Information Network (NIBIN) Allows firearm analysts to acquire, digitize, and compare markings made by a firearm on bullets and cartridge casings maintained by the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) Kendall/Hunt

Chapter 2 Forensic Databases International Forensic Automotive Paint Data Query (PDQ) contains chemical and color information pertaining to original automotive paints maintained by the Forensic Laboratory Services of the Royal Canadian Mounted Police Cross section of Automobile paint Kendall/Hunt

Forensic Databases Shoeprint image capture and retrieval (SICAR) Chapter 2 Forensic Databases Shoeprint image capture and retrieval (SICAR) shoeprint database computer retrieval system - not maintained by a government agency Kendall/Hunt

Chapter 2 Reconstruction The method used to support a likely sequence of events by the observation and evaluation of physical evidence, as well as statements made by those involved with the incident, is referred to as reconstruction. Crime-scene reconstruction relies on the combined efforts of medical examiners, criminalists, and law enforcement personnel to recover physical evidence and to sort out the events surrounding the occurrence of a crime. Kendall/Hunt

The Role of Physical Evidence Chapter 2 The Role of Physical Evidence The physical evidence left behind at a crime scene plays a crucial role in reconstructing the events that took place surrounding the crime. Although the evidence alone does not describe everything that happened, it can support or contradict accounts given by witnesses and/or suspects. Information obtained from physical evidence can also generate leads and confirm the reconstruction of a crime to a jury. The collection and documentation of physical evidence is the foundation of a reconstruction. Kendall/Hunt

Reconstruction Physical Evidence is used to answer questions about: Chapter 2 Reconstruction Physical Evidence is used to answer questions about: what took place how the victim was killed number of people involved sequence of events A forensic scientist will compare the questioned or unknown sample with a sample of known origin. Kendall/Hunt

Chapter 2 Summing It Up Reconstruction is a team effort that involves putting together many different pieces of a puzzle. The right connections have to be made among all the parts involved so as to portray the relationship among the victim, the suspect, and the crime scene. If successful, reconstruction can play a vital role in aiding a jury to arrive at an appropriate verdict. The recognition, collection, and analysis of physical evidence is the foundation to successful reconstruction, but only part of the process. Kendall/Hunt

Chapter 2 Kendall/Hunt

Types of Physical Evidence Chapter 2 Types of Physical Evidence Transient Evidence—temporary; easily changed or lost; usually observed by the first officer at the scene Pattern Evidence—produced by direct contact between a person and an object or between two objects Conditional Evidence—produced by a specific event or action; important in crime scene reconstruction and in determining the set of circumstances or sequence within a particular event Transfer Evidence—produced by contact between person(s) or object(s), or between person(s) and person(s) Associative Evidence—items that may associate a victim or suspect with a scene or each other; ie, personal belongings —Lee and Labriola in Famous Cases, 2001 Kendall/Hunt

Examples of Transient Evidence Chapter 2 Examples of Transient Evidence Odor—putrefaction, perfume, gasoline, urine, burning, explosives, cigarette or cigar smoke Temperature—surroundings, car hood, coffee, water in a bathtub, cadaver Imprints and indentations—footprints, teeth marks in perishable foods, tire marks on certain surfaces Markings Kendall/Hunt

Examples of Pattern Evidence Chapter 2 Examples of Pattern Evidence Pattern Evidence—most are in the form of imprints, indentations, striations, markings, fractures or deposits. Clothing or article distribution Gun powder residue Material damage Body position Tool marks Modus operandi Blood spatter Glass fracture Fire burn pattern Furniture position Projectile trajectory Tire marks or skid marks Kendall/Hunt

Examples of Conditional Evidence Chapter 2 Examples of Conditional Evidence Light—headlight, lighting conditions Smoke—color, direction of travel, density, odor Fire—color and direction of the flames, speed of spread, temperature and condition of fire Location—of injuries or wounds, of bloodstains, of the victim’s vehicle, of weapons or cartridge cases, of broken glass Vehicles—doors locked or unlocked, windows opened or closed, radio off or on (station), odometer mileage Body—position, types of wounds; rigor, livor and algor mortis Scene—condition of furniture, doors and windows, any disturbance or signs of a struggle Kendall/Hunt

Classification of Evidence by Nature Chapter 2 Classification of Evidence by Nature Biological—blood, semen, saliva, sweat, tears, hair, bone, tissues, urine, feces, animal material, insects, bacterial, fungal, botanical Chemical—fibers, glass, soil, gunpowder, metal, mineral, narcotics, drugs, paper, ink, cosmetics, paint, plastic, lubricants, fertilizer Physical—fingerprints, footprints, shoe prints, handwriting, firearms, tire marks, tool marks, typewriting Miscellaneous—laundry marks, voice analysis, polygraph, photography, stress evaluation, psycholinguistic analysis, vehicle identification Kendall/Hunt

Forensic Investigations Chapter 2 Forensic Investigations Include some or all of these seven major activities 1. Recognition—ability to distinguish important evidence from unrelated material Pattern recognition Physical property observation Information analysis Field testing 2. Preservation—collection and proper preservation of evidence Kendall/Hunt

Investigations 3. Identification—use of scientific testing Chapter 2 Investigations 3. Identification—use of scientific testing Physical properties Chemical properties Morphological (structural) properties Biological properties Immunological properties 4. Comparison—class characteristics are measured against those of known standards or controls; if all measurements are equal, then the two samples may be considered to have come from the same source or origin. Kendall/Hunt

Chapter 2 Investigations 5. Individualization—demonstrating that the sample is unique, even among members of the same class 6. Interpretation—gives meaning to all the information 7. Reconstruction—reconstructs the events of the case Inductive and deductive logic Statistical data Pattern analysis Results of laboratory analysis —Lee, Dr. Henry. Famous Crimes, 2001 Kendall/Hunt