Crime Scene Investigation: OF ARTIFACTS AND EVIDENCE
The goal of an archaeological excavation is to carefully collect and record all the available information about a prehistoric or historic site of human activity. The goal of processing a crime scene is to collect and preserve evidence for later analysis and reporting. What these two processes have in common is that they are one-way: Once an action is taken, an artifact moved, a piece of evidence collected, it can’t be undone any more than a bell can be “un-rung.” Crime scenes and archaeological sites are made up of the physical remains of past human activity and, in a sense, are snapshots of the “leftovers” of a completed process. As mentioned previously, when a scene is processed or a site dug, the procedure is one of “careful destruction”: The scene or site will never exist in exactly the same way as it did before the process started. All the information, the relationships, the context of the items must be documented as they are destroyed to allow for some level of reconstruction in the laboratory or museum. It is an awesome responsibility to work a scene or excavate a site, and neither should be taken lightly. Several technical terms that are used in archaeology may be of use in crime scene processing. The first is the idea of a datum, a fixed reference point for all three-dimensional measurements. The datum should be something permanent, or nearly so, like a light switch (pick a corner!), a tree, or a post. If no datum easily suggests itself, an artificial one, such as a post, nail, or mark, can be made. Ultimately, all measurements must be able to be referenced to the datum. Other terms that can be borrowed from archaeology suggest the nature of what is found. An artifact is a human-made or modified portable object. A feature is a non-portable artifact, such as a fire pit, a house, or a garden. Organic or environmental remains (non-artifactual) are natural remnants that nonetheless indicate human activity, such as animal bones or plant remains but also soils and sediments. An archaeological site, then, can be thought of as a place where artifacts, features, and organic remains are found together. Their location in relation to each other sets the internal context of the site. To reconstruct this context once the site or scene has been processed, the investigator needs to locate the position of each item within the surrounding material (the matrix), be it soil, water, or a living room. Thus, the provenance is the origin and derivation of an item in three-dimensional space, in relation to a datum and other items. When an artifact is uncovered at a site, it is measured to the reference points for that excavation unit including its depth. A similar process occurs at a crime scene when evidence is located. As the noted archaeologists, Colin Renfrew and Paul Bahn put it:
In order to reconstruct past human activity at a site it is crucially important to understand the context of a find, whether artifact, feature, structure or organic remain. A find’s context consists of its immediate matrix (the material surrounding it), its provenience (horizontal and vertical position within the matrix), and its association with other finds (occurrence together with other archaeological remains, usually in the same matrix).
The similarities between archaeology and crime scene processing are numerous and deep. Serious crime scene students would do well to study archaeological methods to enhance their forensic skills.
Evidence can be defined as information, whether personal testimony, documents, or material objects, that is given in a legal investigation to make a fact or proposition more or less likely. Most of the evidence discussed in this chapter relates to physical evidence—that is, things involved in the commission of the crime under investiga tion.
