Evidence at a crime scene may be destroyed, altered, or transported by animal behavior. Knowledge about the patterns of animal activity, including scavenging, is important when investigating outdoor scenes.
When bones are discovered at a site, it is critical to differentiate between human and nonhuman bone, as well as materials easily mistaken for bone. Very often, photographs taken at the scene and emailed to a forensic anthropologist (DLF@HumanIDLab.com) can result in rapid identification of a nonhuman bone.
Many different things can disturb the vegetation at a crime scene. Branches can be broken by a vehicle, or even by a human moving through the bushes. Dates of disturbance can be determined by botanical evidence. Layers of leaf litter may have accumulated on the grave and can be counted to assist in determining the season of the disturbance. Roots growing into the body can be aged. Small pieces of plant material found in a grave can be identified and can perhaps tie the suspect to the crime scene. The botanist must have a working knowledge of plant taxonomy, plant anatomy and micro-anatomy, succession patterns, the history of the area, and many other subjects. Ideally, the botanist will have access to the site at the beginning of the search to document as much evidence as possible.
The impact of water on a burial site can be important in terms of atmospheric moisture, surface flow and drainage, soil moisture content, and groundwater flow and drainage. Water chemistry may also impact a site. For example, precipitation patterns and surface flow may relate to the transport of evidence on the surface and the type of vegetation and wildlife present. Variations in soil moisture may be indicative of a disturbance (such as a burial site) and could impact decomposition. Ground and surface water may also be important to the distribution of scent in the area (and may affect the patterns of detection by scent dogs). A hydrologist is usually needed to interpret these water related aspects of a potential burial site.
A meteorologist is able to give specific information for a search area regarding the microclimate and general weather before, during, and after the body's presumed disposal. The conditions before and during body disposal could affect where the body may be deposited. Microclimate at a site is also useful for interpreting the patterns and rates of decomposition. Plant species and stages of growth are affected by climate. Weather events resulting in flooding or erosion could transport or otherwise alter evidence.
A geologist uses knowledge of mineralogy, petrology, stratigraphy, structure, and geomorphology to help recognize and interpret disturbances. Digging a grave disturbs the geology. Soil horizons are disrupted and mixed and material from the depth of the disturbance is moved to the surface. Rocks are re-oriented and the porosity and compaction of the soil is changed. Soil and sediment may be transferred to the perpetrator and to his/her tools.
Geophysical methods are nondestructive and can reduce the time spent on searches. Remote sensing methods include geophysical surveys, which are based on determining contrasts (anomalies) within the subsurface, and can therefore be used to discover disturbances potentially relating to criminal activity. Geophysical techniques can also be used to detect weapons. Many geophysical surveys used by NecroSearch can also be used in water.
Fortunately, computer methods developed for natural resource exploration have been adapted by NecroSearch to search for hidden graves. These programs are executed on laptop computers in the field in order to quickly isolate targets for subsequent excavation. The foundation for these methods involves the superposition of an imaginary grid over the project area. Numeric values corresponding to observations and measurements are assigned to the individual cells within these grids. Separate grids are created for each type of data set. For example, grid "A" might contain soil conductivity measurements while grid "B" might represent the density of a particular plant species within each cell boundary. These grids are then statistically analyzed and combined in order to identify atypical regions, or "anomalies." These anomalies define the exploration targets that merit additional examination.
NecroSearch uses modified archaeological techniques to excavate. Grid construction, sifting, scene mapping and recording are some of the techniques we use to preserve and demonstrate the spatial relationships between any evidence found.
Identification of insect species and observations of their distribution at a site can indicate how long ago a body was deposited and the conditions at the time. Correct collection and preservation is essential.
NecroSearch members are experienced in organized line searches.
Dogs that can detect the odors of decomposition are valuable for detecting human remains, but a dog and handler must be properly trained for this work. Well-meaning volunteers not involved with NecroSearch may claim that their dogs are trained for this work, but caution should be used when employing them.
Sometimes remains of a decedent are located whom authorities are unable to identify. It is the responsibility of the Coroner or Medical Examiner to make such identification. Matching decedent dental, fingerprints and DNA to missing person databases is very effective, however, it requires awareness a person is missing. Many decedents remain unidentified throughout the US as they await their personal data to be entered into such databases as a missing person. This could happen when a family does not want to believe their loved one is deceased.
As trauma, decomposition will render a person unrecognizable, Forensic Art is a tool which allows authorities to provide a presentable image of a decedent to the public in hopes of making an identification.
A Forensic Reconstruction is often requested when other methods of identification have been exhausted and the public’s help is needed. The Forensic Reconstruction is a combination of art and science. A Forensic Artist must work closely with a Forensic Anthropologist to produce a likeness, which when released to the public will trigger recognition.
Tracking may lead to the discovery of a clandestine grave. “Sign” is left behind by the passage of a person; with tracking, we may find further physical evidence and interpretation of a crime scene. Disturbance, compressed areas, dislodged items, even a scuffmark can help determine the line of sign. With the consideration of natural elements and the region, age of sign can be estimated.