Death Scene Procedures:
It is important to note that the collection of insects and other arthropods from a death scene may disturb the remains. Therefore, the forensic entomologist (or the crime scene personnel charged with making the collection) should contact the primary investigator, coroner, or medical examiner and make plans for the collection of entomological evidence. Once a course of action as been determined, utmost care should be taken during insect collection so that the remains are disturbed as little as possible. Before collections are made notes should be taken as to the general habitat, ambient weather conditions, and location of the body. Observations should also be made to describe the microhabitat immediately surrounding the body.
Collection Equipment:
While many of the items needed for the collection of entomological evidence can be purchased from local vendors, so necessary equipment is only available from specialized manufactures. For example, the featherweight forceps that are very useful in larval collection is available from a limited number of sources. For a complete list of collection equipment, look on the collection equipment page.
Scene observations and weather data:
Entomological investigation of the death scene can be broken down into the following steps:
1). Observations of the scene should note the general habitat and location of the body in reference to vegetation, sun or shade conditions, and its proximity to any open doors or windows if recovered within a structure. Locations of insect infestations on the body should be documented as well as noting what stages of insects are observed (such as eggs, larvae, pupae, or adults). It is also useful to document evidence of scavenging from vertebrate animals and predation of eggs and larvae by other insects such as fire ants. Observations such as these can be noted on the Entomological Evidence Scene Form.
2). Collection of meteorological data at the scene. Such data should include:
a). Ambient air temperature at the scene taken approximately at chest height with the thermometer in the shade. DO NOT EXPOSE THERMOMETER TO
DIRECT SUNLIGHT!
b). Larval mass temperature (obtained by placing the thermometer directly into the larval mass center).
c). Ground surface temperature.
d). Temperature at the interface of the body and ground (simply place the thermometer between the two surface.
e). Temperature of the soil directly under the body (taken immediately after body removal).
f). Weather data that includes the maximum and minimum daily temperature and rainfall for a period spanning 1-2 weeks before the victims disappearance to
3-5 days after the body was discovered. Such information can be gathered by contacting the nearest national weather service office, or your state
climatologist.
Collection of insects from the body at the scene:
The first insects that should be collected are the adult flies and beetles. These insects are fast moving and can leave the crime scene rapidly once disturbed. The adult flies can be trapped with an insect net available from most biological supply houses. They are inexpensive and readily obtainable. Once the adult flies have been netted, the closed end of the net (with the insects inside) can be placed in the mouth of a “killing jar” (which is a glass container with cottonballs or plaster soaked with ethyl acetate, or common fingernail polish remover). The jar is then capped and the insects will be immobilized within a few minutes. Once they are immobile they can be easily transferred to a vial of 75% ethyl alcohol. Beetles can be collected with forceps or gloved fingers and placed directly into 75% ethyl alcohol. Proper collection vials (4 dram size) can be obtained here.
It is extremely important that the collected specimens are properly labeled. Labels should be made with a dark graphite pencil, NOT IN INK. The label should be placed in the alcohol along with the specimens, and alcohol can dissolve the ink from the paper! However, pencil is not affected by alcohol and should be used for labeling purposes. The collection label should contain the following information:
1). Geographical Location
2). Date and hour of collection
3). Case number
4). Location on the body where removed
5). Name of collector
**A duplicate label should be made and affixed to the exterior of the vial.**
Once the adults have been collected the collection of larval specimens from the body can begin. First the investigator should search for the presence of eggs, which are easily overlooked. After this step, the larvae should be readily apparent on the body. Generally speaking, the largest larvae should be actively searched for and collected. Additionally, a representative sample of 50-60 larvae should be collected from the maggot mass. These insects can be placed directly into a killing solution or ethyl alcohol. However, the specimens are better preserved if they are placed in boiling water for about 30 seconds. Obtaining boiling water at a scene is difficult, so boiling of the larvae upon returning to the proper facility is satisfactory. If the larvae are boiled with about 48 hours of initial preservation, a good specimen should result. It is important to note that some forensic entomologists prefer not to have the submitted larvae boiled. Therefore, the investigator should discuss preservation techniques with their cooperating entomologist. In any case the exact preservation techniques should be documented and forwarded to the forensic entomologist. If the body has more than one area of colonization (more than one maggot mass) each site should be treated separately.
Once the preserved collections have been made, duplicate samples should be made for live shipment. Living specimens can be placed in specimen containers or Styrofoam cups with tight fitting lids along with some moist paper toweling, or most preferably a food substrate such as beef liver or pork meat. Tiny air holes should be poked in the lid using an ice pick or similar instrument. This cup should be placed into a slightly larger container that has about 1/2 inch of soil or vermiculite in the bottom to absorb any liquids that may accumulate and leak. This entire container should be enclosed in an appropriate shipping container and shipped overnight to a forensic entomologist.
Collection of insects from scene after body removal:
Many of the insects that inhabit a corpse will remain on, or buried, in the ground after the body has been removed. The steps listed above should be followed when collecting insects from the soil (i.e. both a preserved and a living sample should be taken). Soil and litter samples should also be taken both immediately under where the body was positioned, and from the immediate surroundings. It is not necessary to dig deeply. A good technique is to collect the leaf litter and debris down to the exposed upper surface of the soil, and then make a separate collection from about the first two or three inches of topsoil. Each soil collection area should be about 4-6 inches square, and be taken from underneath the head, torso and extremities. All soil samples should be placed in a cardboard container for immediate shipment to a forensic entomologist. These collections should be labeled and forwarded to the forensic entomologist along with the insects collected from the body.
How should insects be shipped to a forensic entomologist?
Properly collected and preserved insects (see above) should be shipped using overnight express either via the United States Postal Service (US Mail), or via the United Parcel Service (UPS). Some shippers will not deliver live insects. Check with your preferred shipper before sending.