Criminalistic laboratory

Given the breadth of forensic science and the varying demands on the criminalistics laboratory, it is not surprising that there is a wide variation in the quality and capability of different laboratories. Limited analyses may be possible at the local level, whereas at regional (e.g., county, state) and federal laboratories sophisticated analytical capabilities may exist. 

Research must be an important component of the university graduate program in forensic science. While such efforts will typically be of longer range significance than found in studies conducted in on-going criminalistics laboratories, it is necessary that the needs of forensic science be always kept in mind. This can only be accomplished by close communication between personnel in the Institute and the forensic science community. 

Measures of performance. In the fall of 1973, three crime laboratories (Contra Costa County, California Dade County, Florida and Columbus, Ohio) were selected as representative sites for the development of measures of performance and effectiveness. The Planning Research Corporation, with Mr. Lowell W. Bradford as Project Director, was awarded the task of developing a conceptual criminalistics laboratory model and methods for measuring the performance of such laboratories. Teams of researchers each spent two months collecting data on the operations of the three previously mentioned laboratories. Data were gathered on the forms of physical evidence submitted and the types of crimes from which the evidence had been recovered. Evidence and cases were traced through the laboratories as examinations were performed and results were formulated. 

The performance measures report is to be published in the near future and will be disseminated to all criminalistics laboratories. The report, although an initial inquiry into a very complex problem, is a major contribution to the literature and should be carefully examined and critiqued by all crime laboratory professionals. Hopefully, it will serve as the basis for future research and refinement of performance models and measures. 

Blood and bloodstain analysis. The Aerospace Corporation has completed a survey and technical assessment of the state-of-the-art of forensic serological practices in the United States. Problems have been defined which currently limit the utilization of blood characterization techniques, and approaches have been identified which have the potential of solving these problems. This assessment was accomplished primarily through contacts with criminalistics laboratories, blood banks, industrial organizations which manufacture instrumentation and reagents for blood identification, and through an extensive search of the literature. 

Computerized Information System. The Project SEARCH Criminalistics Laboratory Information System (CLIS) Committee is another LEAA funded project. Approximately fifteen criminalists are serving on the CLIS Committee which is conducting a requirements analysis for a nationwide computerized crime laboratory information system. With the assistance of a technical subcontractor, PRC Public Management Services, Inc., the committee has determined the "user needs" for such a data system, a conceptual design of a computer system to meet these requirements, and an assessment of different organizational and equipment alternatives for the system. The most recent task reports and implementation plan have been completed and submitted to the advisory committee for final review. Copies of the final reports should be ready for dissemination in the very near future. 

The purpose of this project is to conduct a nationwide criminalistics laboratory proficiency testing program. The objectives of the project are ... 

Through the use of voluntary, anonymous proficiency testing, assess the analytical accuracy of criminalistics laboratories in the processing of selected physical evidence ... 

Other critical steps in the project involve the selection and manufacture of typical evidence according to exact specifications and its distribution to each criminalistics laboratory in the United States, its possessions, and to a group of laboratories in... 

There are wide variations in the nature and magnitude of the caseload and in the manpower and technical capabilities of the nation s criminalistics laboratories (Peterson). Ideally, the crime scene itself should be surveyed by a trained criminalist who is also responsible for the proper collection and transmission of physical evidence. Unfortunately, this practice is only found in the most advanced criminalistics operations, and even here it is almost entirely restricted to major crimes (bombings, homicide, suicide, hit-and-run auto deaths, etc.). While this approach will never be practical for the investigation of all criminal acts, it would permit realistic collection of evidence and its proper transmission to the laboratory for scientific evaluation. The criminalist must be aware of what he is looking for and of the accuracy, precision, and investigative significance of his measurements. 

The final paper in this volume (Jones) is concerned with the application of a less familiar technique, photoluminescence, to a wide range of investigations, including sensitive firearm residue detection, the discrimination between different glass, polymer, and hair samples, and the identification of seminal stains. The promise here is of relatively inexpensive equipment with wide applicability in the criminalistics laboratory. 

Traces are identified by determining their chemical composition and certain physicochemical properties, and comparison with reference material (database) or comparative material collected from the suspect. Criminalistic laboratories create extensive databases on the physical features and production of glass, paints, papers, fabrics and other materials, as well as collecting thousands of samples for comparison purposes. 

The advantages of microspectrometry mean that it is now used in most criminalistic laboratories for examination of traces disclosed at the scene of an event. 

The most common microtraces examined in criminalistic laboratories are so-called contact traces (i.e. small fragments of paint coating, glass, single fibres, soil, writing materials). Moreover, traces of flammable liquids originating from fire debris or traces pointing to the use of firearms are revealed and identified. 

The obtained analytical data allow a conclusion to be drawn about whether the compared paint samples could have originated from the same coat of paint or not. If the reference material (i.e. from the suspect) is not available, only establishment of the kind of paint and the type of paint coat is possible. In the case of automobile paints, it is also possible to find the model of car involved in an accident. Eor this purpose, analytical data are compared with a database containing information about the type of paint coatings (layering, chemical composition of each layer) used in various types and models of vehicles in Europe. Such a collection has existed in Europe since 1995 and is updated every year with information on new products. Experts from many criminalistic laboratories have participated in its creation. Comparison with such a database provides information about the make and model of the vehicle involved in the incident and its year of production. It is thus helpful in identifying the perpetrator s vehicle. It should be emphasised that identifying the make and year of production of a vehicle on the basis of a paint database only applies to vehicles with a factory-new coat of paint. 

Currently applied methods enable easy recovery of trace amounts of flammable liquids, provided that samples are properly collected from the place of fire, saved in hermetic containers and sent directly to a criminalistic laboratory. Figure 11.7... 

A criminalistics laboratory will have a file (that they prepare for their instmment) of chromatograms for several types of gasolines, kerosenes, lantern fluids, lighter fluids, and almost anything that can be easily purchased and used by an arsonist. 

In most cases, the analytical methods of the forensic chemist are different from those of the usual analytical, quality control, or materials chemists. The most important tests are usually those that lead to identification of the substances imder examination. Tests, such as those found in compilations of standard methods of analysis, are rarely of use in the criminalistics laboratory, because they generally require more sample than is available and are usually intended to measure some quantitative aspect of a material. For forensic purposes, initially, a qualitative identification is more important than a quantitative determination. Before the analyst can compare or attempt to individualize a trace sample, it is essential that it be identified. Comparisons performed on traces that have not been accurately identified represent a fault in principle and may come back to haimt the scientist during cross-examination. 

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