Chapter Overview

        A crime laboratory is a scientific organization with a closely dedicated mission of aiding the process of criminal justice. It provides this aid by answering, or helping to answer, the vital question of whether a crime has been committed, how and when it was committed, who committed it, and, just as important, who could not have committed it. The criminal laboratory seeks answers such as these through scientific analysis of physical material collected primarily from the scene of crimes or from suspects. While there are more than 350 federal, state and local crime laboratories across the country, the range of services and personnel expertise within the laboratories, varies among the organizations.

        To understand the role of crime laboratories, one must understand their relationship to the scientific community and to the functions of the criminal justice system. There are two distinct activities involved in laboratory work. One is the gathering of evidence at the scene of the crime by evidence technicians or investigators. The second function is the scientific analysis of evidence, which occurs in the laboratory. The effectiveness of the latter activity often depends on the efficiency with which the first operation is performed.

        An important issue addressed in this chapter conceming the function and responsibilities of a crime laboratory is an investigator's expectations. While the laboratory is one of the most valuable tools for a criminal investigator, he/she must be cognizant of its capabilities and limitations. It is not uncommon, for example, for an investigator to send evidence to a laboratory and stall the investigation until the laboratory results are received. Crime laboratories are not intended to replace field investigations. In addition, investigators are often not familiar with the types of evidence that is subject to laboratory analysis. Even the most minute and seemingly insignificant pieces of evidence may be subject to laboratory examination. If investigators are not aware of a laboratory's capabilities, critical pieces of evidence go uncollected, unprocessed, and unused in substantiating guilt or innocence. Because the analysis of evidence is no better than the samples submitted, investigators themselves play an important role in the success of scientific analysis.