Finding the Crime Scene |
Sometimes forensic archaeologists aren't just called in once a scene has been found, but are asked to help in the search for a missing person. Some of the initial tools they may use to study the area include remote sensing techniques like ground-penetrating radar, soil resistivity, thermal infrared multispectral scanners, or aerial photography. Trained police dogs, volunteers, and search and rescue teams can help search an area for suspicious things like differences in the appearance of soil; mounds of dirt, leaves, or rocks; burnt ground or brush; clothing; or any other unusual or out of place finding. Any of these things or anything a tracking dog reacts to are marked so that a trained forensic archaeologist can study the area. Archaeologists often use a probe, which is placed in the ground at any given interval to determine if any soil feels looser than the surrounding soil. This could be the result of an animal hole or other natural occurrences, but could also be the result of a person burying something. Auger surveying can also show whether the ground has been disturbed. Here's a quick clip that shows some of the tools used to search for a missing person in a real case. History.com Written in Bone: Forensic Anthropology Tools and Techniques |
Excavating the SceneImage from http://jove.geol.niu.edu/students/jpete/fs2006.html
Since the excavation of any archaeological site in essence destroys the site, it is important to conduct a thorough and well-documented excavation of a crime scene, as it is impossible to return to the scene and re-examine the evidence.
One of the most important concepts to forensic archaeologists is that of stratigraphy. Undisturbed soil lies in layers of strata, which differ in color or composition from the layers surrounding them. When excavating a crime scene, forensic archaeologists are able to determine which strata |
existed prior to the burial of evidence. This means that archaeologists may also be able to develop an order of events based on the disturbance of strata. While excavating the scene, forensic experts utilize screens, usually made with 1/4 inch wire mesh so that even small items that are hard to see in the dirt can be found. Other tools of forensic archaeologists are spoons, wooden picks, and small trowels. Heavy equipment is not used, as this could damage important evidence, especially human bones. |
Documenting the Findings
Image from http://whyfiles.org/192forensic_anthro/2.html
Like any archaeological dig, forensic archaeologists use a grid system, datum, and determination of provenience to record and analyze the location of artifacts (or evidence) found at the site. First, a datum is chosen, which is a fixed reference point, chosen so that it can easily be found in the future and is unlikely to move or change. From the datum, a site meridian and baselines are measured. Then, a grid is placed over the area of interest and with the use of stakes and string, a grid is hung, which is a precise, known distance from the datum. Next, digging begins and soil is carefully removed and sifted. Once evidence is uncovered and the ground around it has been removed, the provenience (exact 3D location of an object) of any artifacts that are found is recorded and the item is placed in an evidence bag.
Along with documenting the items removed from the crime scene, forensic archaeologists must also note a variety of other information. This includes documentation of any feature or strata, a log of every item removed from the scene, photographs of items and the excavation site, notes about the surrounding environment, and careful labeling of each of these items. Every item should be labeled and numbered and every photo should give reference to location within the site and give reference to north. The more detail that forensic archaeologists note while excavating the less chance of missing information that cannot be obtained later.
Along with documenting the items removed from the crime scene, forensic archaeologists must also note a variety of other information. This includes documentation of any feature or strata, a log of every item removed from the scene, photographs of items and the excavation site, notes about the surrounding environment, and careful labeling of each of these items. Every item should be labeled and numbered and every photo should give reference to location within the site and give reference to north. The more detail that forensic archaeologists note while excavating the less chance of missing information that cannot be obtained later.
Studying the Bones
The study of human remains and mortuary practices is a subcategory of archaeology known as bioarchaeology. This is extremely important in most forensic archaeology cases, since human bones are often found. Bones can indicated many characteristics of an individual, which may help to identify who the person was or how they died. The pelvis and skull can give sex of the person. Age can be found by studying bone fusion, tooth formation, eruption, decay, and loss. Bone can also show a broken, then healed bone. So if you know that the suspected victim broke their arm 15 years ago and that bone is indeed healed, it may indicated that is the correct person's body. Bones can also be studied for paleopathology, or the study of bones to determine disease or stress on the body. Through paleopathology, forensic archaeologists can determine whether someone did a lot of physical labor, had arthritis, had an iron deficiency, or was malnourished. Certain bones are good predictors of a person's height. One of the most important and more recently available techniques in bioarchaeology is DNA analysis. Sometimes DNA can be extracted from the bones, which is a definite way to determine the identity of the body.
Information to create this page adapted from:
Nawrocki S (1996). An Outline of Forensic Archeology. University of Indianapolis Archeology & Forensics Laboratory (http://archlab.uindy.edu).