Forensic Sciences: Another Introduction

1. Forensic Sciences: Another Introduction

2. 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

3. 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

4. The major areas reviewed INTRO TO FORENSIC SCIENCE 4

5. 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

6. 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. 6

7. 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

8. 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

9. 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 9

10. 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

11. 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. 11

12. 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

13. The work of a Forensic Scientist INTRO TO FORENSIC SCIENCE 13

14. 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

15. 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

16. 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

17. 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

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

19. 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

20. 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

21. 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

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

23. 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

24. 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

25. 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

26. 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