Collecting & Preserving Evidence (Obj 12.6, 12.7, 12.8) Observe and record all pertinent factors Weather patterns (rainfall, wind, humidity, temperature, and exposure to light) during the PMI Avoid disturbing insects within several feet of the body Measure distance from body to insects Collect samples of all insect stages on, near, and under the body Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

Collecting & Preserving Evidence (Obj 12.6, 12.7, 12.8) 1. Estimates on the types and number of insects 2. Key insect colonizations on and near the body 3. Exact positioning of the body using fixed points, if possible: placement of the arms and legs, the position of the head, and parts of the body in the shade and in the sunlight 4. Locations of eggs, larvae, and pupae on the body Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

Collecting & Preserving Evidence (Obj 12.6, 12.7, 12.8) 5. List of opportunistic feeders and other insects (such rove beetles, ants, wasps, and insect parasites) 6. Insect movements (within 20 feet of the body) 7. Natural and artificial influences that might affect the speed of decomposition, such as burning, covering, or burying the body Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

Collecting & Preserving Evidence Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

Factors Affecting Insect Activity Natural environment and natural light Natural environment and artificial light Artificial environment and natural light Artificial environment and artificial light Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

Temperature Readings Ambient air Ground Soil 1 foot above the body 4 feet above the body Ground Soil Surface 10 centimeters below 20 centimeters below Center of a large infestation (if present) Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

More on Collecting and Preserving Capturing live flies with nets Pin flies to a board, or Preserve with 80% alcohol and 20% water Adult flies Eggs Largest larvae Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

More on Collecting and Preserving Label vials with case number collection time date geographic location the location of the insects on the victim the initials of the investigator Forensic Science II: Forensic Entomology, Chapter 12 © 2012 Cengage Learning. All Rights Reserved

Accuracy Insects begin colonizing at a dead body immediately after death Dependent on season and environment Rate of development of the species can be used to estimate time since death Can give an estimate up to a year

Accuracy Entomological evidence is the most accurate and frequently the only method available to determine the elapsed time since death Due to rigor, algor, and livor mortis being useless after 72 hours

Accuracy Insects are also used to Determine whether the body has been moved after death Determine whether it has been disturbed Determine the presence or position of wound sites Determine whether the victim used drugs or was poisoned Determine the length of time of neglect or abuse in living victims

Insect Biology Insects are the most diverse and abundant forms of life on earth. There are over a million described species- more than 2/3 of all known organisms There is more total biomass of insects than of humans. Insects undergo either incomplete or complete metamorphosis (Egg to larva to pupa to insect) Larva have a soft tubular body and look like worms. Fly species larvae are “maggots”

Image: http://www.nlm.nih.gov/visibleproofs