Forensic Sciences: Another Introduction

Science and Law Forensic Science - in its broadest definition is the application of science to law As our society grows more complex, it has become more dependent on laws to regulate the activities of its members. 2

Forensic Science 1-Offers the knowledge and technology of science for the definition and enforcement of laws. 2-It cannot offer final and authoritative solutions, however, Forensic Science does play an important and unique roll in the criminal justice system. 3-It uses the scientist's ability to supply accurate and objective information that reflects the events of a crime 3

The major areas reviewed INTRO TO FORENSIC SCIENCE 4

Forensic Medicine The application of medicine and medical science to legal problems. Practitioners of forensic medicine are doctors of medicine with special certification in pathology & forensic pathology. Most of them are Medical Examiners. They are concerned with determining cause and circumstances in cases of questioned death. They also can be involved in matters of insurance claims, & sometimes cases of malpractice 5

Forensic Odontology Commonly called Forensic Dentistry The application of dentistry to human identification problems. Forensic odontolgists are dentists who specialize in the forensic aspect of their field. They are concerned with the identification of persons based upon their dentition, usually in cases of otherwise unrecognizable bodies or in mass disasters. They also analyze and compare bite mark evidence. Forensic Odontology 6

Forensic Anthropology Personal identification based on bodily remains (particularly skeletal) Practitioners are anthropologists who are interested in Forensic Science. Other areas of forensic anthropology include Maintaining data bases on bodily structures as functions of race, sex, age, stature, and so forth. Facial reconstruction Interpretation of footprint or shoe-print evidence 7

Forensic Toxicology The determination of toxic substances in human tissues and organs. Much of the work concerns the role toxic agents may have played in causing or contributing to the death of a person. 8

Trace Evidence Analysis Includes all areas of trace and transfer evidence: soil and glass hair and fibers blood physiological fluids arson accelerant and explosive residues drug identification patterns and imprints Trace Evidence Analysis 9

Questioned Documents Examination The comparison and interpretation of ... handwriting mechanically produced material (typing, printing) photocopied material The analysis of paper, inks, and other materials used to produce documents 10

Firearm & Toolmark Examination Firearm identification Comparison of markings on bullets, cartridge cases, and shell cases. Determining if a bullet has been fired from a particular weapon. Toolmark examinations are concerned with the association of a particular impression with a particular tool. Firearm & Toolmark Examination 11

Fingerprint Examinations Classification of fingerprints Maintaining fingerprint databases Development and lifting of latent prints Comparisons of known and unknown fingerprints to determine a match 12

The work of a Forensic Scientist INTRO TO FORENSIC SCIENCE 13

The Goals of a Forensic Scientist Recognition of physical evidence Identification of physical evidence Individualization of physical evidence Evaluation of physical evidence Reconstruction of the crime 14

RECOGNITION Although it may seem obvious it is important to be able to recognize what is and is not physical evidence Almost anything can be physical evidence and it is very dependant on the type of crime committed With practice and experience evidence recognition becomes easier Beware…submitting too much evidence is just as bad as submitting too little 15

Identification Identification of physical evidence may be regarded as a classification scheme Evidence is assigned into categories with like items. Initial categories are broad and then narrowed down as more information is obtained Example Blue substance Blue paint Blue car paint Blue car paint from Ford Manufacturing Company Blue car paint from Ford produced 1998-2000 Blue car paint from Ford produced 1998-2000, used on Mustang and Explorer 16

Class Evidence To identify an object in Forensic Science is really to separate it by class Class characteristics are the properties that all the members of a certain group of objects or substances have in common. The previous “paint” example was a refined class evidence identification The “paint” was identified by comparing its class characteristics with those of known standards or previously established criteria. The “paint” is considered CLASS EVIDENCE 17

Class Evidence Examples Single layered paint Soil Glass fragments too small to fit back together Hairs Fibers 18

The Value of Class Evidence Many lawyers try to discredit class evidence because it cannot be limited to just one possible source However Class Evidence DOES HAVE VALUE. Look around room, most have different clothes on. If I were to pick a fiber from one persons clothes in this room, that fiber could possibly pick out the single source or at least narrow the field Some class evidence holds little forensic value such as fiber from jeans or white cotton shirts…they are too common 19

Individualization Individualization is unique to Forensic Science It refers to the demonstration that a particular sample is unique, even among members of the same class. It may also refer to the demonstration that a questioned piece of physical evidence and a similar known sample have a common origin. 20

More Than CLASS In addition to class characteristics, objects and materials possess individual characteristics that can be used to distinguish members of the same class. The nature of these individual characteristics varies from one type to another, but forensic scientists try to take advantage of them in effort to individualize a piece of physical evidence by some type of comparison process. Only a few types of physical evidence (primarily physical pattern evidence) can be truly individualized 21

Evidence that Contains Individualizing Characteristics Fingerprints Handwriting Bullets Toolmarks Shoeprints Tire prints Glass fragments that can be matched 22

Problems with Words Identification is sometimes used to mean personal identification Fingerprints for example, can be used to “identify” an individual The terminology is unfortunate, since this process is really “individualization” Likewise, dental evidence and dental records are used in “identifying” dead bodies...when they are really individualizing 23

The GOAL... Ultimate goal would be to move all class evidence to individualistic, not very likely Hair is trying to make the move...something like paint probably never will. For human evidence to be individualistic, the odds of two people matching the same piece of evidence must be 1 in about 7.5 billion, which is the population of the earth. 24

Is DNA Individualistic?? Up to the late 1990’s, the smallest odds were 1 in 100 million. This narrowed it to 1 in 50 people on the earth, but it still was not individualistic. More recently with new DNA techniques, the new odds are proving to be “individualistic” However we still have the problem of identical twins having the same DNA (but they do have different fingerprints!) 25

Reconstruction Reconstruction refers to the process of putting the “pieces” of a case or situation together The objective is to reach an understanding of a sequence of past events based on the record of physical evidence Identification and individualization of physical evidence plays a crucial role in providing data for reconstructions 26