Forensic Science- Test 2- Chapter 9

Evidence Collection Procedure Sequence

-Visual observations and notations of the scene. -Collect and note climatological data from scene. -Collect insect/arthropod specimens from body and surrounding area before body if removed. -Collect insect/arthropod specimens from under body after it is removed.

Blow Fly

Both a necrophage and a predator. One of the most common species on dead bodies. Often arrive within ten minutes. Feed on any blood or fluids and then start laying eggs in and around the natural body cavities. If the food source is exhausted, they will prey on other species in the same genus. (Chrysomya)

Decomposition Stages

According to Lee Goff, there are 5 stages to body decomposition: -Fresh: from moment of death to visible bloating. -Bloated: Begin when the abdomen starts to inflate. -Decay: Begins when the skins breaks and the gasses escape. Body deflates. -Post- Decay: When only 20% or less of the body weight remains. -Skeletal- When only bones and hair remain.

Temperature

Ambient heat plays a role during egg and early larval development but after that its effect decreases rapidly. Maggot masses generate their own heat.

PMI- Post- Mortem- Interval

An estimation of the duration of PMI involves setting the minimal and maximal time between death and corpse discovery. The minimal PMI is determined largely by estimating the age of developing immature insects collected at the time the body is discovered. The maximum PMI is determined from the species of insects that are present and the weather conditions necessary for the specific activity of these species. ADH-is accumulated degree hours; the amount of thermal energy necessary for the insect to develop to the next stage in the life cycle.

Order of Decomposition

Autolysis- Nonbacterial; breakdown of tissue by body's own chemicals and enzymes; release of gases. Putrefication- Caused by bacteria, leads to slippage of skin, etc. Adipocere - "grave wax"; a grayish white portmortem material caused by fat decomposition Necrophagous Arthopods- -Arrival depends on: - Season or Climate - Situation of the corpse open air, buried iin water; geographic location; cause of death and degree of mutilation.

Hand Collection

Collect a variety of maggots with forceps. Place them in boiling water to stretch them out and fix them. Then, place the maggots into a vial of alcohol with a label containing the date, time, case #, location, and collector.

Metamorphosis

Complete metamorphosis involves development from: Egg to larva to pupa to adult.

Collection

Done in three ways: -Aerial -Hand -Live Sampling

Dr. Neil Haskell

Forensic entomologist affiliated with Jasper Co Sheriff's Department and the Rensselaer, Indiana Police Department Dr. Haskell is nationally recognized for his work as a Forensic Entomology Consultant throughout the United States.

Lee Goff

Forensic entomologist. Program advisor for the forensic science program at Chaminade University in Honolulu, Hawaii. Testified in numerous cases including that of Danielle Van Dam. Consultant on the CBS programs of CSI. Developed a traveling exhibit entitled, "CSI, Crime Scene Insects."

Responsibility

Generally an entomologist is not at the crime scene. The death investigator or evidence technician is responsible for: -Collecting -Preserving -And shipping all entomological evidence.

Larva

Hatch from the eggs and increase in size by growth steps called instars. Become inactive during the pupal stage. During this time the adult insect develops internally.

Critical Scene Temperatures

It is important that at a scene temperatures are taken of these areas in order to ascertain a more accurate determination of time of death: a. ambient b. maggot mass c. body surface d. ground surface -Either soil 3 to 6 feet away from body or water, temperature if applicable. -Under the body surface after it is removed.

Main Types of Carrion Species

Necrophagous- feed directly on the corpse -Files -Beetles Predators -Burying beetles -Rove beetles -Hister beetles -Order of Hymenoptera- ants, bees, and wasps. Species that feed on both the body and other arthropods -Ants -Wasps -Some beetles Arthropods that use the corpse as an extension of their normal habit -Hunting spiders.

Live Sampling

Obtain a styrofoam container with a lid. Use sand or vermiculite for the bottom substrate. Place aluminum foil with beef or pork liver for food on top of the substrate. Collect 10 to 15 live maggots of varying sizes and drop them onto the foul. Close the foil around them and wllow to develop into pupae and then into adults. MUST BE ADULTS IN ORDER TO IDENTIFY THE SPECIES.

Entomology

Study of insects. Insects arrive at a decomposing body in a particular order an then complete their life cycle based on the surrounding temp. By collecting and studying the types of insects found on a body, a forensic entomologist can predict the time of death. Only 7 board certified entomologists in the US.

Aerial Collection

Use a net and sweep it back and forth over the decomposing body. Place them in a large jar with ethyl acetate. After a few seconds, use a funnel to move dead flies into a vial of 75% ethyl alcohol with a label of the date, time, case #, location, sample type and collector.