development. We regard this component as absolutely crucial to the preparation of effective practitioners and have found that field laboratories are eager to accept our student interns. Table 1. Full-Tlme Curriculum for MS Program In Forenslc Sclence FiRST YEAR Fall Quarter
R. E. Gaensslen Oepartmem of Forensic Science University of New Haven Wesl Haven, CT
Thomas A. Kublc Sciemiflc investigation Bureau Nassau County Police Departmem Mineola. NY
Peter J. Deslo
Modern Methods of Analysis Crime Scene Investigation Forensic Toxicology Criminal Justice Process
Department of Chemistry University of New Haven West Haven. CT
Henry C. Lee
Winter Quarter Forensic Materials Forensic Chemistry Techniques i Criminal Law Elective
Connecticut State Police Laboratory Meriden, CT
Spring Quarter Forensic Chemistry Technique I1 Arson. Explosives and Gunshot Residue Criminal Evidence Forensic Serology Summer Quarter in-Service Training SECOND YEAR Fall Quarter Master's Papero Seminar Computers in the Laboratory Forensic Serology I1(elective) or other elective Total Quarter Hours: (Minimum) 47 (Maximum) 51 'The Master's Paper ConstiMes s maja pall of me i i e r ' s s h m i c program. StMento may have wohedon researdlduringtheir acadsmio pmgram, but me paper may also resuit ham wor* m y undertook a.~ a n atheir f internsw It is not the s m e t v m of P r w m of research work namally auociated with an M S or PN) pmgram in chamisby
Table 2. Electlve Coursesa Studenls are required to take two additional courses hom the following list of electives Industrial Hygiene Analytical Separations Electroanaiyticai Chemistry I, I1 Optical Methods of Analysis I, I1 Advanced Organic Chemistry I. I1 Physical Organic Chemistry Polymer Chemistry I, 11. 111 Identification of Organic Compounds Functions of Human Systems Applications of Mass Spectrometry Victimology Women and the Criminal Justice System Science and Technology in Private Security Criminal Justice Planning and Dweiopment Directed Study in Forensic Chemistry Materials Science and EngineeringI, I1 Special Topics in Analytical Chemistry I. 11. 111 Spectrometric identification of Organic Compounds Isolation and identification of Nahrrai Products
Instrumentation and Analytical Methodology in Forenslc Science
concept^ in Pharmacology I. ii Concepts on Toxfcolagy I.ii Enu ronmenta Toxicology Pathology Drug Metabolism Advanced Medicinal Chemistry I. ii Advanced Clinical Chemistry I. 11 Pharmacology of h u g Dependence Biochemistw I. 11. 111 Forensic Serology I1 Cr8mtnal Procedures
Forensic analvsis eenerallv consists of three different components which may he employed in any given case.l.2 Identification refers to the qualitative determination of the identity of a substance, hased on measurements of its physical and chemical properties. Results of such identifications alone do not usually shed much new light on a case; however, there are cases in which the identification of a suhstance comoletes the forensic investieation. A controlled suhstance possession case is a good example of the latter. Not only is identification of the substance all that is reouired of the analyst, but also it is an essential legal requirement if the c h a r ~ eis to he sustained. Indiuidualization refers to the demonstration of common origin between two objects. At present, not many types of evidence can be completely individualized. A true individualization is a demonstration that a sample or item is unique within its own class or that questioned and known samples had a common origin. Reconstruction refers to the establishment of the place, time, and sequence of events that occurred during the perpetration of a criminal act. Complete forensic analysis consists of: (1) recognition of the physical evidence; (2) collection of the physical evidence, observing appropriate preservation and documentation procedures; (3) suhmission of the evidence for analysis; (4) aualysis of the evidence, which may involve identification andlor individualization procedures; (5) interpretation of the results of the examination in terms of the facts of the case; and ( 6 ) an attempt to reconstruct the events and present the results and conclusions to appropriate investigative and judicial bodies. Physical Evldence Because virtually any object or material can be relevant physical evidence in a given case, it is quite difficult t o arrive at a single, suitable classification for physical evidence. A simple classification scheme for such evidence and one that suffices for the present discussion is given in Table 1. A variety of different types of physical evidence is classified in the table according to whether it may be considered physical, chemical, or biological. The focus here is on instrumental methods of analysis, which are most applicable to the evidence classified as chemical or biological. Instrumental methods of analysis as applied to forensic science problems may be looked a t in two ways. One might attempt to categorize the types of evidence that are amena-
' Thornton, J. I., Lex ef Scienfia, 11, (1975).
DeForest, P. R., Gaensslen, R. E., and Lee. H. C., "Forensic Science. An Introduction to Criminalistics," McGraw-Hill. New York. 1983.
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Journal of Chemical Education
Table 1.
Classes and Types of Evldence
Physical
Chemical
Biological
Objects; pieces of objects Plastics (pieces) Glass (pieces) lm~rints lfinaerorints). . ndenrat on9 we mprclsmns) Str at on3 lrltllng impressions on bullets) Physical patterns Firearms, bullets. cartridge cases Toolmarks Ouestianed documents
Drugs and Toxic Substances Paints, pigments Gunshot residues Volatile substances Acce wants. solvents A c o h o l ~(esp ethanol) Rubber materials Resins, plastics Explosive residues Fibers Soil. glass M i s ~ e l l a n e trace o~~ evidence
Blwd Bcdy fluids Hair Tissues Pollen Wood matsrlals Dtner p anlderwed msner Feathers
Table 3.
Some Instrumental Methods and Thelr Appllcablllty to Categorles and Types of Physlcal Evldence Categories and Types of Evidence to Which Applicable
Instrumental Method or Methcdabgy Micr~swpical Visible Polarized Light scanning Electron (SEM)
Spectrophot~metriclSpec~al UltravioletlVisibie Infrared Fluorometry
Table 2.
Some Evldence Types and Applicable lnstrumental Methods
Evidence Woe
Atomic Absorption Atomic Emission
Amlicable InstrumentalMethod
General Examinations; Biological: Questioned Documents Crystals, Minerals. Sails. Paints. Glass. Explosive Residues Gunshot Residue. Paints. Microphy~lcalMatching Drugs. Biochemical Assays, Enzyme Assays. Organic Dyes and Pigments, Inks Drugs, Fibers. Paints, 011s. Plastics. Organics Oils. Fluorescent Organic Substances. Gunshot Residue Gunshot Residue, Ouantitative Elemental Analysis Alloys. Paints, Qualitative Elemental Analysis
other Blood, Bcdy Fluid, Tissue Blood. Body Fluid, Tissuegenetic marker analysis Drugs. Toxic Substances
Paints, Pigments
Spectrophotometry. Enzyme Assays Electrophoresis, lsoelectric
X-Ray Diffractomehy
Focusing UV and IR Spedophot0metry.X-ray Diftractometry, Microscopy. GC/ MS. HPLC IR and Atomic Absorption Spactrophotametry. Polarized Light and Scanning Electron Microscopy, Emission Spectrometry
Mass Spectrometry (inc. GCIMS)
Gunshot Residues
IR Specwophatometry. Polarized Light MiCrOSCOpy. HPLC Neutron Activation Analysis, Atomic Absorption Spectrophotometry, SEM .-
Accelerants. Solvents Ethyl Alcohol (Blood or Breath)
Gas Chromatography Gas Chromatography, Enzyme
Hair
Microscopy, Electrophoresis, lsoelectric Focusing Polarized Light Microscopy. IR and Visible Spectrophotometry. Mi~ro~peCtrOphotometry (UV, VlS, IR)
Explosives Residues
Neutron Activation Analysis
ChromatographicISeparatian Thin-Layer (TLC) Gas Chromatography (GC) Liquid Chromatography (HPLC)
Drugs, Crystals. Minerals, Alloys. Metals Organic Substances, Drugs, Accelerants. Mixtures of Organics Gunshot Residue. High Sensitivity Elemental Analysis Drugs, hks. Pigments. Pollutants Volatiles. Solvents, Alwhois. Toxins, Accelerams Drugs, Paints. Explosive Residues. Toxins Protein and lsoenzyme Genetic Markers. Bcdy Fluids Protein and lsaenzvme Genetic Markers of Blood. Bod" Fluids
Couplsd Assay
Fibers
ble to instrumental analysis and match them with the applicable instrumental methods (see Table 2). Alternatively, one might first try to classify the different types of instrumental methods and indicate next to them the types of physical evidence for which they might serve as useful analytical tools (see Table 3). Analytical Methods
Most analytical methods having identification of a substance as their objective are comparatively straightforward. There are identification problems in which combinations of instrumental analyses have made possible more definitive results. The identification of gunshot residue particles provides an example. Samples that are examined by elemental analvsis techniaues (AA. NAA, etc) and found to contain appropriate les,elsor antimmy, barium, and lead are consistent in elemental wn~oosirionwith ~ u n s h o tresidut.. While this information alone-does not prove the sample's identity, using a combination of SEM, which enables the gunshot residue particles to he visualized, and X-ray elemental analysis, which can show that the particles have the appropriate elemental composition, makes the identification virtually certain.
In very many cases and situations, individualization of the evidence is the desired " eoal. Instrumental methods of analviis u,hich have individualization as their objective must be caoable of detectinr dit'ferenrrs in samoles of rhe same mateiial which are o f t k exceedingly min&.e. As a result, bulk chemical analvsis techniques have not proven very successful for individualizations, particularly k i t h small samples. Better results have been obtained with methods that measure the distribution of components, compounds, or elements alone with the nature and quantity of them. Many for&sic analyses involve the comparison of a known (or exemplar) sample with an unknown (or questioned) one. Useful comparisons of complex samples are possible using instrumental methods even when the procedure does not allow the examiner to discover the actual composition of the samples. Examples of such comparisons are the comparison of two paint samples by IR and the comparison of two complex automotive engine oils by spectrophotofluorometry. Generallv soeakinp, the ability to individualize a sample of physicai e;idencewould pro;ide much more conclusive information about a case. At the present time, most comparisons involving instrumental methods lead to one of two conclusions. Either the samples do not match and are thus demonstrated to be different, or they do match and are then said to be "similar" or "consistent with having shared a common origin." Advances
The future undoubtedly holds the key to more well-defined identifications and better individualization of many Volume 62
Number 12 December 1985
1059
types of physical evidence. Achievement of this goal would make the information supplied by forensic scientists more useful and would assist in arriving a t more precise reconstructions of events in cases. Instrumental methods of analysis will certainly play a major role in the progress that is made.3 Approaches that yield information about the distribution of components of a sample as well as about their nature offer one avenue of future research. The individualization of some types of evidence is made difficult by the fact that the variation of some property within a single sample may be as great or greater than the variation hetween two different samples. Methods and methodologies must, therefore, be sought that can exploit variations in composition or distribution of components that are greater between similar specimens than within them. Another approach that may be explored is the use of
1060
Journal of Chemical Education
combinations of instrumental methods for comparisons of auestioned and known samoles. In this wav. s~ecimenscan de compared with respect tb a number of diffkrent properties, making-the orobabilitv of common origin when . - greater . no differences are detected. Advances in the analysis of materials in the forensic science laboratory tend to parallel advances in other areas of chemistry. The fact that the samples found in the forensic laboratory are usually small has led to techniques that are nondestructive and require only small amounts of sample. Modern instruments provide great utility in this regard, leading to the promise of continued advances.
'Williams,
R. L., Anal. Chem..45, 1076A (1973).
