Forensic Science

4 An Introductory Forensic Science Course in a Law Enforcement Program RICHARD SAFERSTEIN New Jersey State Police, Trenton State College, and Ocean County College, N. J. 08625

Downloaded by SUFFOLK UNIV on January 22, 2018 | http://pubs.acs.org Publication Date: June 1, 1975 | doi: 10.1021/bk-1975-0013.ch004

ROBERT EPSTEIN New Jersey State Police, Paterson State College, and Essex County College, N. J. 07102

The past ten years have seen a tremendous growth i n the number of law enforcement or c r i m i n a l j u s t i c e programs o f f e r e d a t two- and four-year c o l l e g e s . While some of these programs might be regarded as mere extensions of i n - s e r v i c e t r a i n i n g courses, most have been incorporated i n t o a liberal a r t s program that i s designed to provide the student with a knowledge of b a s i c academic subjects while emphasizing a s o c i a l science c u r r i c u l u m that r e l a t e s to the concepts, problems and techniques of law enforcement. Often, the d i s t i n c t i o n between a t r a i n i n g course that emphasizes v o c a t i o n a l a p p l i c a t i o n and one that attempts to t r e a t a c r i m i n a l j u s t i c e t o p i c on the context of modern s o c i a l problems is difficult to d e f i n e . A comprehensive d i s c u s s i o n of the philosophy, goals and accomplishments of higher education law enforcement programs can be found i n recent government p u b l i c a t i o n s (1, 2 ) . While law enforcement programs have a t t r a c t e d numerous students who may have otherwise avoided a higher education, they have at the same time c o n t r i b u t e d to a developing e d u c a t i o n a l problem; that is, how to o f f e r meaningful and productive c o l l e g e l e v e l courses to a student who does not have the proper academic foundation. Nowhere has t h i s problem been more acute and the responsive e f f o r t s more d i v e r s e than i n the p h y s i c a l sciences (physics and chemistry). The glamour that science held i n the post-sputnik era has long s i n c e disappeared i n our high schools and c o l l e g e s . The present-day student seems to consider a science course a b e t t e r pill to swallow. In response, educators have been developing a number of p a l a t a b l e science courses f o r the nons c i e n t i s t . Most of these e f f o r t s have been p r e d i c a t e d on the o v e r r i d i n g philosophy that science will only be comprehensible when the subject matter can be r e l a t e d to popular and motivating contemporary problems. Hence, courses have been devised that

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Davies; Forensic Science ACS Symposium Series; American Chemical Society: Washington, DC, 1975.


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incorporate and r e l a t e science to problems of modern l i f e , f o r example, environmenta1 and h e a l t h problems and space e x p l o r a t i o n (3-_6). In a law enforcement program, a course on F o r e n s i c Science o f f e r s i t s e l f as an i d e a l v e h i c l e f o r i n t r o d u c i n g the student nons c i e n t i s t to many of the b a s i c concepts and p r a c t i c e s o f chemist r y and b i o l o g y while i l l u s t r a t i n g t h e i r a p p l i c a t i o n s to c r i m i n a l i n v e s t i g a t i o n s , a subject that has d i r e c t relevance to the student's v o c a t i o n a l and/or academic i n t e r e s t s . Such a course has been s u c c e s s f u l l y introduced i n t o two four-year c o l l e g e s and two two-year c o l l e g e s i n New Jersey during the past three years. The f o r e n s i c course has s e v e r a l o b j e c t i v e s . F i r s t , to help the student understand the r o l e of the s c i e n t i s t and the crime l a b o r a t o r y i n the c r i m i n a l j u s t i c e system. The nature o f p h y s i c a l evidence i s emphasized along with the l i m i t a t i o n s that modern technology imposes on the i n d i v i d u a l i z a t i o n and c h a r a c t e r i z a t i o n of such evidence. The l o g i c a l procedures and methodology o f s c i e n t i f i c i n q u i r y with respect to the a n a l y s i s of c r i m i n a l evidence i s d i s c u s s e d . P a r t i c u l a r a t t e n t i o n i s p a i d to the meaning and r o l e of p r o b a b i l i t y i n i n t e r p r e t i n g the s i g n i f i cance of s c i e n t i f i c a l l y evaluated evidence. A c l e a r d i s t i n c t i o n i s drawn between the i n d i v i d u a l and c l a s s c h a r a c t e r i s t i c s that p h y s i c a l evidence may possess. F i n g e r p r i n t s and t o o l marks exemplify the former while a blood type or s o i l specimen may be i n d i c a t i v e o f the l a t t e r . Wherever p o s s i b l e , d i s c u s s i o n o f the types o f p h y s i c a l evidence commonly encountered a t the crime scene i s accompanied by s t a t i s t i c a l data that r e l a t e s to i t s p r o b a b i l i t y of occurrence i n a defined p o p u l a t i o n . A second aim i s to introduce the student to the theory and techniques of the f o r e n s i c s c i e n t i s t . I t i s here that a b a s i c d i s t i n c t i o n i s made i n the philosophy and o b j e c t i v e s of a f o r e n s i c science course as compared t o one that i s soley devoted to the techniques of c r i m i n a l i n v e s t i g a t i o n . The student i s taken beyond a mere d e s c r i p t i v e explanation of the a n a l y s i s and i s introduced to b a s i c b i o l o g i c a l and chemical concepts underl y i n g the i d e n t i f i c a t i o n of p h y s i c a l evidence. Obviously, i t i s not the i n t e n t o f the subject matter t o make a f o r e n s i c expert o f the student. For t h i s reason the chemistry and b i o l o g y taught i s l i m i t e d to the minimum core o f f a c t s and p r i n c i p l e s needed to make the techniques of a f o r e n s i c s c i e n t i s t comprehensible to a n o n - s c i e n t i s t . The task i s a formidable one. Experience has shown that l e s s than 5% o f the student enrollment has had a science course on the c o l l e g e l e v e l . Furthermore, any knowledge that may have been gained from high school science courses has long been f o r g o t t e n . Any i l l u s i o n s that the i n s t r u c t o r may have had about p r i o r student knowledge i s q u i c k l y d i s p e l l e d d u r i n g an i n t r o d u c t o r y l e c t u r e on metric measurements. The d i f f i c u l t i e s encountered i n e x p l a i n i n g the concept o f a decimal system along with the necessary mathematical procedures needed f o r c o n v e r t i n g



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FORENSIC SCIENCE

E n g l i s h system measurements i n t o metric equivalents q u i c k l y enl i g h t e n s the i n s t r u c t o r to the abhorrence that the n o n - s c i e n t i s t has towards mathematical manipulations. No p r i o r knowledge of s c i e n t i f i c p r i n c i p l e s can be assumed. In our opinion, those subjects which have not been found to be e a s i l y i n t e g r a t e d with chemical and b i o l o g i c a l p r i n c i p l e s are best omitted from the f i r s t course of study. Hence, f o r e n s i c photography, the p o l y graph, document examination and speed detection devices are t o p i c s that are not included i n the curriculum. A t h i r d o b j e c t i v e of the course i s to emphasize the importance of the r o l e that the proper r e c o g n i t i o n , c o l l e c t i o n , and p r e s e r v a t i o n of p h y s i c a l evidence has i n c r i m i n a l i n v e s t i g a t i o n . The s o p h i s t i c a t e d techniques of the modern f o r e n s i c laboratory may be rendered meaningless i f the f i e l d i n v e s t i g a t o r cannot properly present evidence to the crime laboratory. Therefore, the c o r r e c t packaging and handling of such evidence i s s t r e s s e d along with adequate sampling procedures. Even more fundamental i s the development of the understanding of what a c t u a l l y c o n s t i tutes p h y s i c a l evidence. As so often i s the case, i n v e s t i g a t o r s w i l l c o l l e c t extraneous materials at the crime scene simply out of an unawareness of the c a p a b i l i t i e s of the f o r e n s i c l a b o r a t o r y . S i m i l a r l y , meaningful evidence may go undetected or u n c o l l e c t e d because an i n v e s t i g a t o r has no a p p r e c i a t i o n f o r the l i m i t s of d e t e c t i o n that accompany microscopic and instrumental techniques of a n a l y s i s . Readings of case h i s t o r i e s are presented to f u r t h e r i l l u s t r a t e the p r a c t i c a l s i g n i f i c a n c e that s c i e n t i f i c a l l y examined p h y s i c a l evidence may have i n c r i m i n a l i n v e s t i g a t i o n s . Course

Outline

The f o r e n s i c science course o f f e r e d can be a four-hour course that combines l e c t u r e s with laboratory exercises or three hours of i n s t r u c t i o n c o n s i s t i n g of l e c t u r e s and several l a b o r a tory demonstrations. A b r i e f o u t l i n e of the course curriculum i s presented f o r both the l e c t u r e and laboratory components of the course.

I.

II.

Lectures Introduction A. D e f i n i t i o n and h i s t o r y of f o r e n s i c science B. Organization and s e r v i c e s of our f o r e n s i c laboratory C. Function of the f o r e n s i c s c i e n t i s t D. Legal aspects of f o r e n s i c science The nature of p h y s i c a l evidence A. I n d i v i d u a l and c l a s s c h a r a c t e r i s t i c s B. The s i g n i f i c a n c e of p r o b a b i l i t y i n c r i m i n a l evidence i n v e s t i g a t i o n


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VIII. IX.

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XI. XII. XIII.

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P h y s i c a l p r o p e r t i e s of matter A. Units of measurement B. Determination of mass, volume and temperature C. Density and r e f r a c t i v e index Forensic p r o p e r t i e s of glass and s o i l Organic a n a l y t i c a l techniques A. Theory and f o r e n s i c a p p l i c a t i o n s of t h i n - l a y e r and gas chroma to graphy B. Theory and f o r e n s i c a p p l i c a t i o n s o f spectrophotometry Inorganic a n a l y t i c a l techniques A. Theory and f o r e n s i c a p p l i c a t i o n o f X-ray d i f f r a c t i o n , emission spectroscopy, and neutron a c t i v a t i o n Microscopy A. The theory and use of the compound, s t e r e o s c o p i c and comparison microscopes Forensic examination o f h a i r s , f i b e r s and p a i n t Forensic serology A. Composition o f blood and semen B. ABO system C. F o r e n s i c c h a r a c t e r i z a t i o n o f d r i e d blood and semen D. P r i n c i p l e s of h e r e d i t y F o r e n s i c drug i d e n t i f i c a t i o n and t o x i c o l o g y A. Microscopic and instrumental techniques f o r i d e n t i f y i n g commonly abused drugs B. The theory and a p p l i c a t i o n of the b r e a t h a l y z e r F i n g e r p r i n t i d e n t i f i c a t i o n and c l a s s i f i c a t i o n Firearm and toolmark i d e n t i f i c a t i o n Explosives and arson i n v e s t i g a t i o n A. The chemistry of combustion B. The d e t e c t i o n of explosive and gasoline Laboratory

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residues

Exercises

Measurement of the density of glass by f l o t a t i o n P a r t i c l e density d i s t r i b u t i o n o f s o i l (density gradient tube) F a m i l i a r i z a t i o n with the compound and s t e r e o s c o p i c microscopes


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4.

6. 7. 8.

Microscopic i d e n t i f i c a t i o n and comparison of h a i r s and fibers F o r e n s i c presumptive t e s t s f o r blood and semen - whole blood typing Microscopic i d e n t i f i c a t i o n of marihuana Color and m i c r o c r y s t a l t e s t s f o r commonly abused drugs Latent f i n g e r p r i n t i d e n t i f i c a t i o n

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The preparation and examination of casts and molds


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Discussion Though i t i s not p r a c t i c a l to describe the depth of i n s t r u c t i o n o f f e r e d f o r each t o p i c covered, a b r i e f d e s c r i p t i o n of the subject of spectrophotometry can serve to i l l u s t r a t e the a u t h o r s general approach to teaching a f o r e n s i c science course to the nonscientist. The student i s f i r s t introduced to the wave and p a r t i c l e concepts of l i g h t . Though minimal emphasis i s placed on mathem a t i c a l equations, the r e l a t i o n s h i p between v e l o c i t y , wavelength and frequency, as w e l l as the c o r r e l a t i o n of energy to frequency, i s described. Those regions of the electromagnetic spectrum that are most u s e f u l and convenient f o r c h a r a c t e r i z i n g chemical substances are emphasized. The s e l e c t i v e absorption of u l t r a v i o l e t , v i s i b l e and i n f r a r e d r a d i a t i o n by molecules i s explained i n a d e s c r i p t i v e manner that s t r e s s e s how the noncontinuous energy requirements of chemical substances can only be s a t i s f i e d by photons that have energy values equivalent to that of the d i f f e r e n c e s i n energy l e v e l s of the molecule i n question. The meaning and q u a n t i t a t i v e s i g n i f i cance of Beer's Law i s b r i e f l y discussed. The components of a simple spectrophotometer are i l l u s t r a t e d , accompanied by a demonstration of the operation of a spectrophotometer i n the l a b o r a t o r y . A c t u a l a p p l i c a t i o n s of the techniques of s p e c t r o photometry are described during the presentation of r e l e v e n t t o p i c s , f o r example, i n drug i d e n t i f i c a t i o n . Unfortunately, there i s at present no a v a i l a b l e textbook which combines a d i s c u s s i o n of the r e l e v e n t fundamental chemical and b i o l o g i c a l p r i n c i p l e s of f o r e n s i c science with t h e i r a p p l i c a t i o n s to the i d e n t i f i c a t i o n and comparison of p h y s i c a l evidence. Paul K i r k ' s recent text (7) does o f f e r a comprehensive i n s i g h t i n t o f o r e n s i c techniques. However, although the text i s an e x c e l l e n t c o n t r i b u t i o n to f o r e n s i c l i t e r a t u r e , i t does not e n t i r e l y f u l f i l l the o b j e c t i v e s of the course we have described. In p a r t i c u l a r , the book does not introduce the reader to the theory and meaning of fundamental p h y s i c a l and chemical propert i e s of matter that are r e l e v e n t to f o r e n s i c a n a l y s i s . A d d i t i o n a l l y , the book i n many instances assumes p r i o r knowledge of many of the a n a l y t i c a l techniques of f o r e n s i c chemistry. ?


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H. J . Walls' text (8) i s a f a i r l y recent treatment o f i n t r o d u c tory f o r e n s i c science that c l o s e l y p a r a l l e l s our course's curriculum. Unfortunately, t h i s text i s out o f p r i n t and i s no longer a v a i l a b l e . Therefore, the student must r e l y on l e c t u r e notes f o r reference during a s i g n i f i c a n t p o r t i o n of the course.


Conclusion The success of an i n t r o d u c t o r y course on f o r e n s i c science f o r the n o n - s c i e n t i s t w i l l be dependent on the i n s t r u c t o r ' s a b i l i t y to s e l e c t those m o t i v a t i n g t o p i c s that w i l l s t i m u l a t e thought and understanding of r e l a t e d s c i e n t i f i c p r i n c i p l e s . Once the student comprehends the techniques and l i m i t a t i o n s of the f o r e n s i c s c i e n t i s t , a meaningful understanding o f the n e c e s s i t y of c o l l e c t i n g and p r e s e r v i n g p h y s i c a l evidence develops. In t h i s manner a f o r e n s i c science course serves as a v e h i c l e f o r i n t r o d u c i n g the law enforcement student to s c i e n t i f i c p r i n c i p l e s and techniques while simultaneously p r o v i d i n g p r a c t i c a l v o c a t i o n a l a i d to the p r a c t i s i n g or a s p i r i n g c r i m i n a l i n v e s t i g a t o r . I t i s i n t e r e s t i n g to note that r e s u l t s obtained from anonymous student e v a l u a t i o n s of the course showed that more than 90% of the students f e l t the course f u l f i l l e d or exceeded t h e i r expectations. Literature Cited I.

2.

3. 4. 5. 6. 7. 8.

"Introducing a Law Enforcement Curriculum a t a State Univers i t y , " U.S. Government P r i n t i n g O f f i c e , Washington, D.C., 1970. "Higher Education Programs i n Law Enforcement and C r i m i n a l J u s t i c e , " U.S. Department o f J u s t i c e , U.S. Government P r i n t i n g O f f i c e , Washington, D.C., 1971. Cassidy, H. G., J. CHEM. EDUCATION (1971), 48, 212. Fahrenholtz, S., J. CHEM. EDUCATION (1973), 50, 499. Mechstroth, W. K., J. CHEM. EDUCATION (1974), 51, 329. F u l l e r , E. C., J. CHEM. EDUCATION (1974), 51, 260. K i r k , P. L., "Crime I n v e s t i g a t i o n , " (1974), John Wiley & Sons, New York, New York. Walls, H. J . , "Forensic Science," (1968), Praeger P u b l i c a t i o n s , New York, New York.


Forensic Science

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