CRIMINALISTICS
Geoffrey Davies Institute for Chemical Analysis, Applications and Forensic Science Northeastern University Boston, MA 02115
Criminalistics, which is part of the wider field of forensic science, is concerned with the collection, laboratory evaluation, and interpretation of physical evidence arising from a crime or a suspicious incident (e.g., an unexplained death) (1). A great variety of evidence material is submitted to the crime laboratory for evaluation as part of the investigative and judicial processes. The current heavy workloads of crime laboratory personnel are largely the result of two factors: • The rapidly increasing crime rate • The greater emphasis which is being placed on physical evidence in the courts as a result, in part, of the report from the President's Commission on Crime in 1967 (2). The greater utilization of physical evidence in the investigative and judicial processes has created career opportunities for chemistry graduates, as well as providing challenges for educators and researchers in contributing to the overall effectiveness of criminalistics laboratory operations. Previous articles (3-6) have focused on the function, status, and needs of the criminalistics profession. A symposium, "Educational and Scientific Progress in Forensic Science," which was cosponsored by the Analytical and Chemical Education Divisions of the ACS and the American Academy of Forensic Sciences at the recent ACS National Meeting in Atlantic City,
provided a useful forum for the discussion of current educational and scientific progress in criminalistics. This article will summarize the topics presented at the symposium. Before delving into this, however, it will be useful to review the criminalistics operation so that the later discussion can be put into perspective.
Nature of Criminalistic Investigations As noted above, criminalistic investigations are essentially a service function of the investigative and judicial systems. Although the detailed chain of events which leads to court testimony by an expert witness depends to some extent on the type and circumstances of a particular crime, the criminalistic investigative process can be broadly broken down into four phases: • Collection of evidence • Laboratory measurements • Interpretation of results • Court testimony. The actual caseload often places heavy demands on the facilities and manpower of the criminalistics laboratory. Also of importance is the legal requirement that the integrity of each item of evidence be preserved throughout a particular case. This requirement calls for an efficient criminalistics operation at the local level (7).
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Collection of Evidence The manner in which the crime scene is searched and evidence is selected and preserved is crucial to the criminalistics operation (7). The person collecting the materials must not only attempt to reconstruct the crime but must also appreciate the potential value of each type of evidence in the investigation. Since the laboratory criminalist is in the best position to seek and select the evidence which is most likely to be amenable to useful laboratory measurement and interpretation, it can realistically be argued that a laboratory criminalist should supervise the search and collection phase. However, the existing heavy caseloads in most American laboratories preclude the direct involvement of criminalists in the collection phase; even in the most advanced judicial systems (5, 7, 8), direct involvement is almost entirely restricted to major crimes (e.g., bombings, homicide, suicide, and hitand-run incidents). This calls for a substantial training program for policemen, firemen, and evidence technicians, emphasizing the importance of proper evidence collection. A number of criminalists are actively involved in such educational efforts, which serve to increase the effectiveness of the overall criminalistic operation. Laboratory Measurements Among the types of evidence sub-
EDUCATIONAL AND SCIENTIFIC PROGRESS mitted to the laboratory are solid materials (glass, fibers, soils, paint chips, charred wood, discharged bullets), biological samples (whole blood, blood and seminal stains), samples obtained from suspects (personal property, hand swabs, blood and urine samples), and impressions obtained from the crime scene (footprints, toolmarks, fingerprints). In many cases, the laboratory seeks evidence which will prove the truth or otherwise of the victim's, suspect's, or eyewitness' statements. The choice of an analytical procedure for the detailed examination of a particular item of evidence depends on many factors, including likely identifying characteristics and the nature of the crime. T h e crime laboratory must have the facilities and expertise to apply a wide range of analytical procedures to the spectrum of evidence material. In addition, the criminalistic team must often be selective in its choice of evidence for evaluation, especially when items have been indiscriminately collected and the laboratory caseload is large. T h e majority of analyses carried out in the criminalistics laboratory are comparative, in t h a t they are aimed at establishing that two pieces of material have a common origin. Even today, the simple, compound or comparison microscope is the most widely used instrument. An increasing number of examinations now involve the identification and quantitative determination of particular elements, compounds, or characteristics under difficult analytical circumstances. A particularly good example is the absolute determination of the levels of Sb and Ba in a hand swab obtained for analysis of gunshot residue by neutron activation (9) or flameless atomic absorption spectroscopy (W).
In general, analytical measurements must be objective, inexpensive, rapid, and reproducible to be compatible with time and manpower constraints. The aim of current research is to improve the capabilities of established laboratory techniques and to encourage the use of newer methodology (scanning electron microscopy, highspeed liquid chromatography, and electroanalysis) in the evaluation of a wide range of physical evidence materials. Interpretation of Results T h e goal of laboratory measurements is to determine the nature and origin of a particular item of evidence: the basis for interpretation depends on the evidence class and the procedure used for identification. A few examples will serve to illustrate the different kinds of information which are necessary to draw conclusions for commonly occurring types of physical evidence. T h e comparison microscope is used in many laboratories to visually compare the rifling and firing pin impressions on a bullet recovered from a crime scene with those of a test bullet fired from a suspect weapon. If a weapon has not been recovered, the bullet may be compared with items in a reference collection so t h a t the type of weapon, and possibly its owner, can be established. However, recovered bullets are often badly deformed, making identification difficult and sometimes impossible. Similarly, ink identification by thin-layer chromatography (11) is based on a comparison of the sample chromatogram with those of a reference collection of inks: this data base allows the establishment of criminal forgery and the backdating of questioned documents.
Report
T h e genetic typing of bloodstains (12) is based on the different electrophoretic properties of known protein phenotypes. Here, t h e availability of a number of genetically independent " m a r k e r s " allows interpretation through the consideration of population distribution data (5). T h e establishment of a significantly high level of a particular drug or toxin in a sample is also based on a comparison with statistical data, obtained from general population studies (4). There are two important boundary conditions in crime laboratory evaluations: • There are often time and other constraints on the number of different measurements t h a t can be made on a given item of evidence. The criminalist must be familiar with the most distinctive identifying features and must understand the basis of comparison of his measurements with test or reference data. • Since the conclusions are essentially a determination of the probability of criminal involvement, they are useless in the absence of clearly defined and distinguishable standards, either from test samples, reference collections, or statistical background
data. Court Testimony It takes several years of criminalistics experience to qualify as an expert witness. Senior laboratory personnel spend a considerable amount of their time in court, sometimes defending conclusions which may depend on analyses made by technicians or other personnel. The expert witness must not only be conversant with the legal and scientific basis of his testimony, but must also be prepared to give a detailed account of the experimental procedure, the statistical basis for the
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conclusions drawn, and the legal and scientific precedence for such conclusions (13). An example of the significance of cross-examination is provided by the current, close questioning of computer-based data and of automated analyses. The court may disregard the physical evidence, not on the basis of the measurements themselves, but because the witness is unconvincing in his presentation of the data because of his lack of background knowledge. Aspects of Symposium Proceedings The symposium program was roughly divided into educational and technical aspects of forensic science, although these are, of course, very strongly interrelated. R. F. Turner of Michigan State University provided a perspective of the current problems in education and training, pointing out the historical aspects of the field which often provide precedents on which to base court testimony. He expressed the opinion that most courses being offered today are simply inadequate for the needs of the profession in that they do not include historical perspective. William McGee of Florida Technological University in Orlando carried out a very careful assessment of the current status of the profession before initiating a new undergraduate program in Forensic Science at FTU. The curriculum for this program (Table I) is based on a heavy concentration in the physical sciences, with the balance of credit hours being taken up in courses concerned with the examination of particular classes of evidence. The instructors for these special topics are to be practicing criminalists, a valuable feature from the viewpoint of relevance. A very strong component of practical field experience is evident in this program and should be an integral part of any course which is intended to train professionals. The creation of a completely new course of this type is expensive; however, given the fact that most universities are capable of providing the basic science and legal courses, the only elements to be added are the special coverage of forensic science topics and the internship. Two criminalists (Richard Saferstein and Robert Epstein of the New Jersey State Police Laboratory) presented their experience in teaching introductory forensic science courses at a number of state and county colleges. The major problem in these courses is the poor academic backgrounds of the students, and Saferstein and Epstein thus teach basic science courses, using forensic topics as applications (Table II). However, the technical criminalis-
Table f. Undergraduate Forensic Science Program at Florida Technological University First Year
Fall
Biological Science Chemistry
Biology General
Communication Mathematics Social Science Second Year Chemistry
English Precalc. Organic Analyt.
University Studies Restricted Electives" Physics Third Year Law & Legal Procedure Forensic Science Restricted Electives Social Science Statistics Summer Following Third Year Fourth Year Internship University Program English Restricted Electives Social Science
Microbiol. Physics
For. Anal. 6 Phys. Chem. Social Sci. Stat.
Winter
Spring
Botany General Gen. Lab Speech Calculus
Microbiol. General Analyt.
Organic Analyt. History Immunology Physics
Organic Organic Lab Humanities Serology Electronics
Law Crmnl. Ie Phys. Chem.
Legal Proced. Crmnl. II Adv. Analyt
Computer Sci. Social Sci.
Cooperative Education Internship Internship Univ. Prog. Report Writing For. Sci. Social Sci.
Univ. Prog. For. Sci. Total Quarter Hours: 180
" Restricted électives are approved courses in science, forensic science, legal procedure, or criminal justice. i> Forensic Analysis Techniques. c Criminalistics.
tic level is limited, and these courses cannot be regarded as a source of professional criminalists. Rather, they provide an appreciation of criminalistics for the police officer and layman and in this regard are important in advancing the status of physical evidence in the judicial process. Given the continuing tendency toward liberal education at our undergraduate colleges, the need for specialized, technical training at the graduate level is becoming evident. Although there are a limited number of graduate programs which are well regarded by the profession, these are too few to satisfy the increasing manpower and technical demands of the Nation's criminalistics laboratories. Barry Karger, director of the newly established Institute of Chemical Analysis, Applications and Forensic Science (ICAAFS) at Northeastern University in Boston, surveyed the situation in graduate education and research as regards forensic science. Northeastern University is part of a consortium of schools across the nation which was established by the Law Enforcement Assistance Administration of the Department of Justice (LEAA) to develop effective training and research programs in law enforcement. The educational and research goals of ICAAFS have been identified as a result of a careful study of the needs of the forensic science profession. A master's program in forensic chemis-
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1975
try (Table III) has been developed, and a doctoral degree program is planned. As can be seen from the table, these programs will contain a core of existing courses in science and law from a number of university departments and will be supplemented by specific criminalistics courses taught by experienced professionals. There will be a strong internship component in both programs, and all students will be involved in criminalistics research. The current research programs at ICAAFS are concentrated in the applications of materials science and biochemical analyses to forensic science. Particular emphasis is being placed on rapid separation and identification methods which can be applied in the average criminalistics laboratoryFurther details of the goals of LEAA and of current and projected research programs were provided by Joseph Peterson (now at John Jay College, CUNY); each research proposal is carefully reviewed by established, practicing forensic scientists to determine its feasibility and immediate and long-term usefulness to the profession. Among projects which have recently been funded are: • A study of the availability and qualifications of scientific personnel and of regular proficiency testing (the Forensic Sciences Foundation) • A study of the management and . evaluation of criminalistics laboratory
Table II. Course Outline for Forensic Science Program Offered in Mew Jersey State College System LECTURES i. I n t r o d u c t i o n A. D e f i n i t i o n a n d history of forensic science B. Q r g a n i z a t i o r a n d services of our forensic laboratory C. F u n c t i o n of t h e forensic s c i e n t i s t D. Legat a s p e c t s of forensic science II. T h e N a t u r e of Physical Evidence A, I n d i v i d u a l a n d class characteristics B. T h e significance of p r o b a b i l i t y in c r i m i n a l e v i d e n c e investip,atior. I I I . Physical Properties of Matter A, U n i t s of m e a s u r e m e n t B, D e t e r m i n a t i o n of m a s s , v o l u m e , a n d t e m p e r a t u r e C, Density a n d refractive i n d e x IV. Forensic Properties of Glass and Soil V. Organic Analytical Techniques A. Theory and forensic a p p l i c a t i o n of thin-layer and fcav rhroni;-:tCuf>iphy Β. T h e o r y a n d forensic a p p l i c a t i o n s of s p e c t r o p h o t o m e t r y VI. Inorganic Analytical Techniques A. T h e o r y a n d forensic a p p l i c a t i o n of X-ray d i f f r a c t i o n , e m i s s i o n spec t r o s c o p y , a n d n e u t r o n activation V I I , Microscopy A. T h e t h e o r y a n d use of t h e c o m p o u n d , stereoscopic an;l cor^pr-r-ïon: microscopes V I I I . Forensic Examination of Hairs, Fibers, and Paint IX. Forensic Serology A. C o m p o s t i o n of b i o o d a n d s e m e n B. A B O s y s t e m C. Forensic c h a r a c t e r i z a t i o n of d r i e d b l o o d a n d s e m e n D. Principles of h e r e d i t y X. Forensic Drug Identification and Toxicology A. Microscopic a n d i n s t r u m e n t a l t e c h n i q u e s for i d c i i i i i y m c ; c o m m o n l y abused drugs B. T h e theory a n d a p p l i c a t i o n of t h e breathalyser X I . Fingerprint Identification and Classification X I I . F i r e a r m and Toolmark Identification X I I I . Explosives and Arson Investigation A. T h e c h e m i s t r y of c o m b u s t i o n B. T h e d e t e c t i o n of explosive a n d gasoline r e s i d u e s 1. 2. 3. 4. 5. 6. 7. 8. 9.
LABORATORY EXERCISES M e a s u r e m e n t of t h e d e n s i t y of glass by flotation Particle density d i s t r i b u t i o n of soli ( d e n s i t y g r a d i e n t t u b e ) Familiarization w i t h t h e c o m p o u n d a n d stereoscopic m i c r o s c o p e . ; Microscopic i d e n t i f i c a t i o n a n d c o m p a r i s o n of hairs a n d f i b o i ζ Forensic p r e s u m p t i v e t e s t s for b l o o d a n d s e m e n — w h o l e b H o i i r v p ' n g Microscopic i d e n t i f i c a t i o n of m a r i j u a n a Color a n d m i c r o c r y s t a i tests for c o m m o n l y a b u s e d d r u g s Latent fingerprint identification T h e p r e p a r a t i o n a n d e x a m i n a t i o n of casts a n d m o i d : ;
Table III. Curriculum for Master's Degree Program in Forensic Chemistry at Northeastern University Fall Quarter
QH°
First Year Instrumental Analysis
4
Crime Scene Investigation
Forensic Materials
2
Administration of Criminal Justice Biochemistry 1
3
Forensic 4 Chemistry Techniques 1 Seminar (or 1 Spring)
Second Year Master's Paper Biometrics Electives
2
Winter Quarter
QH 3
Concepts in Toxicology 1
2
Elective
2
Spring Quarter
QH
Forensic C h e m - 4 istry Tech niques II Arson and 3 Explosives Seminar (or Winter)
1
Legal Aspects of Forensic Science Elective
3
Summer Quarter
QH
In-Service Training*
2
4 2 2
" QH = quarter hour: 43 quarter hours of credit are required for graduation. 6 No aca demic credit is given for in-service training.
operations (Planning Research Corp., L. W. Bradford, project director) • Blood and bloodstain analysis (Aerospace Corp. and the Pittsburgh and Allegheny Crime Laboratory). These are programs to encourage wider implementation of existing techniques for dried bloodstain analy sis (12) and to develop further tech niques for the individualization of physiological fluids and dry fluid sam ples. • Standard reference collections (NBS). Most criminalistics laborato ries depend, at least to some extent, on a reference collection of hair sam ples, color codes for paints, and the like. This project seeks to systematize these collections and to provide upto-date reference materials. • Computerized information sys tem. This is a study of the require ments for a nationwide computerized crime laboratory information system being carried out by the Project SEARCH Criminalistics Laboratory Information System Committee (CLIS). Many laboratories maintain files (e.g., of latent fingerprints) which are difficult to use because of time constraints imposed by inadequate classification schemes. Bradford and Samuel (1) emphasized the tremen dous advantage of on-line computer file searches at the local level, and the initial phase of identification could be made more efficient in this manner, with the final step of identification being performed by established com parative analysis techniques. • Variant polypeptides in hair. This study is aimed at the genetic typing of hair samples through analysis of the variants of structural proteins (Massa chusetts General Hospital). • Characterization and individuali zation of semen. Again, the goal of this research is to individualize physiolog ical fluid samples through genetic polymorphisms (Berkeley). LEAA is also currently involved in the establishment of rigorous criteria for evaluating new techniques and data for use in court, initially through a standing committee of leading judges, attorneys, and scientists. These studies would supplement the ongoing work of the Association of Of ficial Analytical Chemists in establish ing standard analytical procedures. Solid Samples Applications of powerful materials science techniques to forensic science problems are becoming more wide spread. Although the equipment is ex pensive, restricting its present use largely to regional and federal labora tories, there is the promise of further instrumental development to enable increased application at the local level. Because of its capabilities in im-
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Figure 1 . Scanning electron m i c r o g r a p h r e c o r d s of firing pin impressions on t w o c a r tridge c a s e s Casing on left recovered from river sometime after homicide committed. Casing on right fired from suspect weapon in laboratory. Because of effects of submersion, comparison by conventional microscopy virtually impossible Courtesy of Gary Judd and coworkers
proving the depth of field and its ready extension to energy dispersive analysis (EDA) of the elemental composition of surfaces, the scanning electron microscope is finding useful application. The SEM might be used to detect erased serial numbers because the sample subsurface'retains some of the special properties caused by the initial serialization. Bullets, paint chips, "unknown substances," and cement and glass fragments can be identified rapidly by combined SEM and EDA analysis. Figure 1 illustrates a comparison (by Gary Judd of Rensselaer Polytechnic Institute and coworkers) of a test cartridge case with a sample which had been recovered from a river some time after a homicide had been committed. The variation in depth of surface features between the test and sample is easily overcome by SEM, and analysis of the persistent features enables identification. Donald Polk and Bill Giessen of ICAAFS have devised a powerful tagging system for guns which employs laser drilling of up to 10 readily deciphered digits in an area of % X % in., which is normally that required for just one digit of a conventional serial number (Figure 2). The great advantage of this system is that the identification can be situated in an inaccessible part of a gun so that erasure would require virtual destruction of the weapon's action. The manufacturing cost of serialization by laser drilling has been estimated at only $0.05 per gun. The laboratory caseload of recovered bullets is usually very large (Detective Johnson reported that in 1973 the New York City Police Department processed 16,184 cases involving 16,850 individual firearms, using an 324 A ·
open evidence file of more than 25,000 specimens which dates back to the 1930's). Among the techniques holding promise for improving the efficiency of bullet identification is the SEM, coupled with a computerized data base. Fourier transform techniques might also be applicable, although the significant differences between the surface detail of the deformed evidence and test samples are difficult to resolve. The examination of suspected arson debris is aimed at establishing the use of incendiary substances (gasoline, kerosine, alcohol) with criminal intent. If the article has been packed in an air-tight container, headspace sampling frequently enables identification
of the volatile components by gas chromatography. Steam distillation followed by GC is often useful for the remainder. However, Cecil Yates of the FBI Laboratory pointed out that adulterants such as plasticizers wreak havoc with gas chromatographic columns, and it is difficult to maintain a reference collection of incendiary substances because of frequent formulation changes by manufacturers. There is considerable potential in the use of high-pressure liquid chromatography in the fingerprinting of arson debris. [Recent work at Waters Associates (14) has shown that gradient elution, reverse-phase chromatography is capable of separating and quantitating the additives in petroleum samples and that high-pressure gel permeation chromatography is suitable for the separation and identification of lowmolecular-weight plasticizers such as phthalates.] Two other techniques are worthy of special mention in that they offer the possibility of wide analytical application of single instrument systems at the local level. The first is differential scanning calorimetry, which Hall and Cassel of Perkin-Elmer Corp. have shown to be diagnostically powerful in the individualization of y^in. lengths of hair and other polymers. Single strands of hair and clothing material comprise an important class of evidence material which often defies conventional microscopic identification. The advantage of differential thermal methods is that they allow the identification of man-made fibers: each sample has a thermogram which exhibits characteristics of a specific processing history (15). A sample size-
Figure 2. Serialization by laser drilling Serial number 5383158068 on right can be read by reference to grid formed by holes at extreme left and right Courtesy of Donald Polk and Bill Giessen
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1975
Figure 3. Thermalmechanical analysis thermogram of single fiber of untextured cellulose triacetate. Thermogram reflects processing history of sample Courtesy of Perkin-Elmer Corp.
Table IV. S a m p l e Size-Limited Test Schedule 1. Weigh sample 2. TMA (0-120°C) Obtain glass transition, stress relief and cold recrystallization temperatures Obtain weight of de3. Reweigh hydration Obtain processing 4. DSC points, melting (100-300°C, N,) profile, and/or crosslinking exotherm Then DSC 1-20" to 5. Shock-cool 300°C) 6. Program-cool Obtain degree of supercooling, fusion profile 7. Slow heat Obtain conditioned melting profile Obtain degradation 8. TGS or DSC (200-700°C) or profile analyze by other means
limited test schedule illustrating the thermalmechanical analysis (TMA) and differential scanning calorimetry (DSC) capabilities of a modular instrument system is illustrated in Table IV. Figure 3 shows a TMA thermogram of a single fiber of untextured cellulose triacetate; the normal thermal expansion of the material at low temperatures is followed by contraction as water is lost above 100°. The 5% expansion associated with the glass transition at 180° is followed by contraction before melting/decomposition, properties which are diagnostic of triacetate; in particular, the transition temperatures are characteristic of individual samples. Other major
Figure 4. Identification of rayon, cotton, and wool by DSC in inert atmosphere DSC profiles characteristic of individual samples. Conditions: range, 10 m e a l / sec. full scale; atmosphere. N 2 ; scanning rate, 4 0 ° C / m i n Courtesy of Perkin-Elmer Corp.
classes of fibers (polyacrylonitriles such as orlon and acrilon) and rayon and cotton show no distinctive thermal features up to 300°, but "fingerprints" can still be recognized in the absence of oxidative decomposition by heating the sample in an inert atmosphere (N 2 , argon) (Figure 4). A second technique which holds considerable promise for operationally simple and widespread use in criminalistics is photoluminescence, which may be defined as the light emitted by a sample in the 300-700-nm region on excitation with UV (190-380 nm) radiation. Useful analytical parameters are: the emission and excitation spectra (the latter is defined as the variation of luminescent intensity at fixed wavelength as the wavelength of the excitation source is varied; the decay time of the luminescence once the excitation source has been extinguished; and the quantum yield of emission. The analytical advantages of these methods are substantial: • Highly selective—absorption, emission, and lifetime parameters of evidence and test specimens must all match • Highly sensitive (1 ng for efficient emitters) • Often nondestructive • Inexpensive • Often do not require preseparation of the sample. The current research at Aerospace Corp. (P. Jones) aims at extending the capabilities of the conventional qualitative inspection of evidence for forgery, the location of body fluid stains, spots in paper and TLC chromatography, and the usual comparison of oils, greases, paint chips, and glass frag-
ments, to quantitative analysis of a wide range of forensic materials. Luminescence decay curves (e.g., of aromatic hydrocarbons in polymer matrices) are nonexponential because of the anisotropic environment of the solute (16), and the sensitivity of the luminescence of a molecule or atom to its microenvironment has been shown to be extremely valuable in the individualization of clue material. Luminescence decay properties can be used to detect semen (77), which is a difficult problem using conventional colorimetric or microcrystal formation techniques. Electrophoresis (18) enables the separation of seminal acid phosphatase from vaginal fluid, and the former can be positively identified even in the absence of spermatozoa (which is the case in about 50% of the samples examined). The technique is also applicable to gunshot residue analysis: low-temperature (77°K) luminescence from chlorocomplexes of lead (II) and antimony (III) at 276, and 250 and 300 nm, respectively, allows simultaneous detection of these elements in gunshot residue at the 110-ng level in less than 30 min. The analysis of gunshot residues was the subject of two other papers at the symposium. Edgars Rudzitis (Illinois Bureau of Investigation) and Maurice Wahlgren (Argonne) have improved the sample capacity and statistical evaluation of neutron activation analysis, and William Kinard and Donald Lundy (Bureau of ATF, Washington) have shown that flameless atomic absorption measurements give comparable data at the microgram level for arsenic and antimony residues. Photoluminescence analysis
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further improves the sensitivity by three orders of magnitude, with analy sis times comparable to flameless AA. These latter methods may be more ap plicable to the local laboratory t h a n is NAA and should lead to much wider local utilization of residue analysis. T h e refractive indices of 143 glass samples from California criminalistics laboratories have been measured by Peter Jones and his coworkers: about 50% of these samples had refractive indices in the range 1.5160-1.5180, making conventional comparison vir tually impossible. Thirteen of these samples phosphoresced with broad bands at 540 and 730 nm; however, at fixed excitation wavelength and exci tation source intensity, the different ratios of the peak absorbances allowed 12 of the 13 samples to be distin guished. Photoluminescence is clearly a very powerful, yet simple technique for the individualization of glass sam ples. The sensitivity of tryptophan and tyrosine emission to the microenvironment is a potential means of indivi dualizing single strands of hair (19). Hair strands from eight light-colored individuals which could not be distin guished by conventional microscopic techniques were excited at 250 nm and 77° K. Although phosphorescence decay characteristics did not differ sufficiently to allow clear distinction between samples, individualization was still possible on the basis of their distinct phosphorescence spectra (Fig ure 5). [The availability of relatively inex pensive spectrofluorimeters that give spectra which are automatically cor rected to eliminate artifacts owing to variations of the excitation source in tensity and detector response as a function of wavelength is an impor tant recent development in forensic analysis. The corrected excitation spectrum is identical to the absorption spectrum but with a thousandfold in crease in sensitivity for fluorescing substances such as quinine and mor phine (as pseudomorphine). A fluo rescent substance can thus be posi tively identified by comparison with standard absorption spectra (rather then uncorrected fluorescence spectra which depend on the particular instru ment on which they were measured), and the analysis of mixtures of very dilute fluorescent materials can be made by conventional techniques without the need for separation. The only requirements would seem to be that the absorbance of the solution be less than ca. 0.05 in the 200-700-nm region, and t h a t the substance(s) have a fluorescence peak at a longer wave length than the solvent spectral cut off.] An elegant example of the applica 326 A ·
tion of a well-established technique (thin-layer chromatography), backed by a comprehensive reference collec tion, is provided by the ink identifica tion capability of the Bureau of A T F (Richard Brunelle, chief, Identifica tion Branch). By use of TLC with a comparatively small range of solvent systems, inks can be readily identified as microsamples which leave the ques tioned document intact for other anal yses (e.g., of handwriting). Ink formu lations generally contain enough com ponents to allow direct, qualitative comparison with library data, espe cially when the chromatogram is ex amined both visually and under ultra violet light. This technique has been accepted as definitive evidence by the courts in quite a number of recent cases. Manufacturers have been very cooperative in providing samples of commercial inks, and A T F is trying to encourage more frequent formulation changes and specific tagging to allow more precise dating of questioned doc uments. Genetic Markers Over the past few years there have been several notable advances in the applications of forensic serology in the evaluation of important classes of clue material such as blood and seminal stains. The goal of workers at the FBI and Pittsburgh and Allegheny County crime laboratories is to identify genet ic markers whose population frequen cies have been firmly established. These markers are inherited indepen dently of one another, and a marker profile will permit a mathematical probability of uniqueness to be calcu lated. Obviously, the greater the num ber of markers, the higher is the prob ability of a unique identification (5). Three classes of blood constituents are useful for the establishment of mark ers, namely, the blood grouping and typing antigens, polymorphic en zymes, and polymorphic proteins (12). T h e conventional ABO and M N systems have well-established frequencies. T h e Rh system, which is not so widely used as the other two, has a five-component antigen system giving rise to eight agglutinogens. Use ful data for the British population have been summarized by Williams (5). T h e Pittsburgh group has suc ceeded in shortening the ABO blood grouping of just three bloodstained threads to 45 min/sample. Electrophoretic separation and identification of typable isozymes are gradually gaining acceptance in North America. However, the typing of evi dence depends on careful control of experimental procedures and the availability of reliable statistical data. Recent work at the FBI Laboratory in Washington by C. G. McWright and
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Figure 5. Phosphorescence spectra at 77°K for hair of two different individuals at three different excitation wavelengths Significant variation of phosphorescence intensi ties evident on changing excitation from 250 to 350 nm. - - - 250 nm; — 300 nm; 350 nm Courtesy of Peter Jones
coworkers has been focused on the es tablishment of optimum conditions for the electrophoretic typing of erythrocytic acid phosphatase (ΕΑΡ) phenotypes. A study of the distribu tion of five ΕΑΡ phenotypes in 137 randomly selected Washington, DC, residents gave results in good agree ment with those of Giblett and Scott (20). T h e FBI studies indicate that the incidence of ΕΑΡ phenotypes is not associated genetically with blood groups ABO, MN, and Rh. The third main class of genetic markers in blood consists of the poly morphic proteins, which include he moglobin and the haptoglobins. He moglobin typing is useful for the iden tification of fetal and negroid blood (21). Peptidase A and glutathione re ductase have also been found to exhib it polymorphism in negroid blood, with little or no variation in Cauca sians. The Pittsburgh group is further exploring typing schemes in the Gm and Inv immunoglobins (so far, 23 Gm and 3 Inv types have been found, but success is predicated by the availabili ty of antisera) and is also applying ra dioimmunoassay to quantitate testos terone and estrogen in dried blood to determine the sexual origin of very small samples.
P G M and lactate dehydrogenase (LDH) may be developed on the same zymogram. LDH-4 and L D H - 5 phenotypes are elevated in menstrual blood stains even after two weeks. A new band, currently labeled LDH V , ap pears between L D H - 3 and LDH-4 as a result of spermatogenesis a n d can be detected even when semen is absent in the sample (22). Current work indi cates t h a t a t least five constituents of seminal fluid can be electrophoretically separated a n d antigenically intro duced into rabbits, and t h a t acrylamide electrophoresis of acid phospha tase, A P , is useful when vaginal swabs are being tested for seminal fluid; however, it is still only a presumptive test until the specific source of the AP can be identified. F u r t h e r develop m e n t of simple and accurate typing methods is clearly an i m p o r t a n t as pect of current criminalistics practice.
Figure 6. GC separation of trimethylsilyl derivatives from her oin sample 1, Morphine-TMS; 2, codeine-TMS; 3, C^-monoacetylmorphine-TMS; 4, acetylcodeine; 5, heroin. Direct chromatography of samples under compara ble experimental conditions does not resolve acetylcodeine and C^-monoacetylmorphine Courtesy of Stanley Sobol and Albert Sperling
Drug Identification and Analysis Drug identification and analysis is a d o m i n a n t feature of the caseload of many criminalistics laboratories. Re search concerned with the establish m e n t of standard methods of identifi cation and q u a n t i t a t i o n of drugs, drug metabolites, and toxins continues to be an active area in forensic science (23). Advances in this area are thus of great interest to criminalists, and pa pers on this topic gave rise to lively discussion at the symposium. Forensic toxicology has been de fined by Finkle (4) as the evaluation of the harmful effects of exogenous substances on living systems in t h e medico-legal context. T h e three major caseload areas which d o m i n a t e foren sic toxicology are: • Illegal use of drugs • Broad, criminalistic investigations • P o s t m o r t e m cases. Definitive interpretation of the evi dence is d e m a n d e d by the courts in all cases. As a result, an increasingly so phisticated range of analytical tech niques is being applied to meet the legal requirement for absolute quanti tation of even micro- and picogram/ml levels of drugs a n d drug metabolites in physiological samples. T h e methods of widest potential application are based on separations by gas or high-pressure liquid chromatography coupled with mass spectrometric detection. Abso lute identification of very low levels of drugs, drug metabolites, and toxins is then possible through comparison with s t a n d a r d mass spectra (24). T h e establishment of illicit narcot ics sources is of particular interest to the Drug Enforcement Administra tion, where workers in the Special Testing a n d Research Laboratory (S. P. Sobol, chief) have investigated di rect and derivative GC m e t h o d s for
the fingerprinting of drug exhibits. Adulterants in heroin samples include monoacetylmorphine, acetylcodeine, opium alkaloids (introduced during production) and quinine, procaine, methapyrilene, and various sugars (in troduced at the street level). T h e iden tification of as many constituents as possible is the goal in the "fingerprint ing" of drug samples. Derivatization (involving t r e a t m e n t with Λ/,Ο-bis(trimethylsilyl)-trifluoroacetamide) gives clean separation of morphine, codeine, 0e-monoacetylmorphine, ac etylcodeine, and heroin in about 20 min (Figure 6). T h e minor constitu ents (morphine and codeine) can be detected at the 15-25-ng level. These chromatographic techniques have been successfully used for court testi mony and are representative of a major c u r r e n t emphasis on developing new methodology in criminalistics. T h e Atlantic City symposium pa pers, which will be published shortly as a volume in the "ACS Symposium Series," will serve as a useful guide to c u r r e n t educational and scientific progress in forensic science.
References (1 ) L. W. Bradford and Α. Η. Samuel, "Law Enforcement—Science and Technology," Vol III, ρ 465. Academic Press, New York, NY, 1970. (2) "Task Force Report: Science and Technology," President's Commission on Law Enforcement and Administration of Justice, Washington, DC. 1967. (3) J. M. English, Anal. Chem.. 42 (13), 40A (1970). (4) B. S. Finkle, ibid., 44 (4), 18A (1972). (5) R. L. Williams, ibid., 45 (13). 1076A (1973).
(6) Chem. Eng. News, ρ 13 (Feh. 5, 1973). (7) R. H. Fox and C. L. Cunningham, "Crime Scene Search and Physical Evidence Handbook," U.S. Department of Justice, 1973; J. L. Peterson, "Utilization of Criminalistics Services by the Police—An Analysis of the Physical Evidence Recovery Process," National Institute of Law Enforcement and Criminal Justice, 1972; G. B. Stuckey, "Evidence for the Law Enforcement Officer," 2nd éd., McGraw-Hill, New York, NY, 1974. (8) T. Kondis, Renaissance 1'ittsburgh, ρ 28, September 1974. (9) R. R. Ruch, V. P. Guinn, and R. H. Picker, Nucl. Sci. Eng.. 20, 381 (1964); V. P. Guinn, R. P. Hackleman, H. R. Lu kens, and H. L. Schlesinger, USAEC Report GA-9882, Department of Commerce, Springfield, VA, 1970. (10) G. D. Renshaw, CRE Report 103, Home Office Central Research Establishment, Aldermaston, Berks., England, 1974. (11) R. L. Brunelle and M. J. Pro, J. Assoc. Of fie. Anal. Chem., 55, 823 (1972). (12) B. J. Culliford, "The Examination and Typing of Bloodstains in the Crime Laboratory," National Institute of Law Enforcement and Criminal Justice, Washington, DC, 1971. (13) A. A. Moenssens, R. E. Moses, and F. E. Inbau, "Scientific Evidence in Criminal Cases." Foundation Press, Mineola, NY, 1973. (14) W. A. Dark, Waters Associates, Milford, MA, private communication, 1974. (15) W. M. S. Philp, J. Forensic Sci., 17, 132 (1972); W. P. Brennan, "Therm. Anal. Appl. Studies," 6, Perkin-Elmer Corp. Publication TAAS-6. 1972. (16) P. F. Jones and A. R. Calloway, J. Chem. Phvs., 51, 1661 (1969). (17) P. F. Jones, A. R. Calloway, D. J. Carre, and S. Siegel, J. Forensic Sci. Soc, in press. (18) E. G. Adams and B. G. Wraxall, Forensic Sci.. 3, 57 (1974). (19) S. V. Konev, "Fluorescence and Phosphorescence of Proteins and Nucleic Acids," ρ 147, Plenum Press, New York, NY, 1967.
ANALYTICAL CHEMISTRY. VOL. 47, NO. 3. MARCH 1975 · 329 A
CVP The analyzers'
Somerimes
