Forensic chemistry: An introduction to the profession

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Forensic Chemistry-A symposium collection ---

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Introduction to the Forensic Chemistry Collection Thr articles i n this rollrrtwn emerged 25 a r e d t of 1noS)mpo.i~ un f~~rrns~cchemisrry-the fir%twas held asa par1 of the 78th AI'S meeting in Sruttir, U'dahingtun, i t , hlarrh. 1Yd:l. mu t h e s e n d at the oth BwnnralCanf~rence irn rhpmiral cdurarim in Srcrrrs, Connrctirut, in uyust. ID3 I. 'l'hr objectivv uf thi* toilwtim i\ tu prwrdc teacher* otchemistry with ample resource material so that they might add forensic chemistry units to enhance the relevancy of their courses and introduce forensic chemistry as a profession and possible career choice for their students. Topics range from development of forensic science laboratory courses and mock-crime scenes to forensic serology and analytical techniques.

Keith Berry

Henry E. Outlaw

Department of Chemistry University of Puget Sound 1500 N. Warner Tacoma, WA 98416

Depanment of Physical Sciences Delta State University Cleveland. MS 38733

Forensic Chemistry: An Introduction to the Profession Keith Berry University of Puget Sound Tacoma. WA 98416 George G. Ishli Western Washington Crime Laboratory seanle, WA 98104 In this oaoer we hooe to communicate some of the characteristics df the profession of forensic chemistry, and some of the requirements f w persons in the field, from the viewooint of an kducator, a practitioner, and a laboratory director. This information may help persons interested in the discipline or the profession make judgments for further action. While forensic chemistry is essentially the application of chemistry to all matters of law, we will limit ourselves to the area of criminal justice, thereby foregoing any discussion of civil procedures and requirements. The California Association of Criminalists describes the profession as "That orofession and scientific discioline directed to the resoynilion, identification, individualization of the and evnluarion ofnhvsiral e\,idence hv the aoulicntion .. natural sciences to caw-science I t further states, "It involves the application of principles, techniques and methods of the natural sciences, and has as its primary objective a determination of physical facts which may be significant in legal case^."^ Characterlsllcs of the Profession Forensic chemistry and analytical chemistry consider similar auestions includine" what andlor how much of a given item is in a given sample. There are, however, several other important anestions with which forensic chemists are concerned. ~ h e would k like to know what the sample originally was, where i t came from, what was the source, and how it got from one place to another. For instance, a chemist may he able to determine if a particular liquid is water; the forensic chrmisr may wish to know where &at water came from. To do this he or shr will have to harea method to determine, for

example, if i t was lake water, sea water, water from a particular chemical synthesis, or from a particular chemical processing plant. The forensic chemist is likely to he interested in whether the sample shares a commonality of origin with another sample on hand. He or she is likely to he interested in finding a reasonable explanation for its presence a t a oarticular place and will be-interested in experiments that wiil connect or relate the sample or evidence to the victim or suspect. As society has-aged and technology has advanced, there are solutions now available for problems that used to he unsolvable. Problems related to the examination of nhvsical evidence from crime scenes persist in providing interesting challenaes for chemists. We will illustrate a tvoical case. Consider a case in which a driver in a sto~eiEarstruck and killed a pedestrian. The impact was so areat that the driver struck his head against the windshield breaking the glass and cutting his head. He fled the scene and there were no witnesses, but due to the severity of the injury he went to a hospital for treatment. During the police investigation they questioned a doctor and nurse who had treated a patient with a head injury; the nurse had shaved hair from the suspect's head and had not yet disposed of the hair. Examination revealed that the hair had not only been cut by the nurse a t the hospital, but at the other end of the hair shaft glass fragments were adhering to the hair. The glass was compared with samples taken from the windshield, while the hair was compared with hair samples removed from the car. Both types of samples compared favorably, the hair being consistent with having come from the same origin, the glass fragments exhibiting the same physical properties (density, refractive index, optical dispersion) as that from the windshield. Essentially, the chemist answered such questions as what the material was, how it got there, whether it was there at the time of impact, and whether there was a commonality of source. Forensic chemistry requires knowledge of other disciplines. Biochemistry is used in bloodstain

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' Kingston, C. R., A.S.T.M. Standard. News, 1 [4], 8 (1973).

Davis, J. E. (Editor),"Code of Ethics," California Association of Criminalists. adopted May, 1957. Volume 62

Number 12 December 1985

1043