Forensic entomology
- 1. Significance of Insects in Forensic Entomology Present By Logeswaran V 2020505014 ENT 504 CLASSIFICATION OF INSECTS (1+1)
- 4. • Forensic entomology is the application and study of insects and other arthropods biology to legal issues, especially in a court of law. • These insect colonizers can be used to estimate the time of death i.e., time interval between death and corpse discovery, also called Postmortem Index (PMI), movement of the corpse, manner and cause of death and association of suspects at the death scene.
- 5. • Sung Tz'u (1235 AD) – Chinese “death investigator” wrote “The Washing Away of Wrongs”. • First forensic entomology case recorded - A murder by slashing occurred in a village, and the local death investigator was ordered to solve the crime. The investigator had all villagers bring their sickles to one spot and lay them out before the crowd. Flies were attracted to one of the sickles, probably because of invisible remnants of tissue still remaining on it, and the owner subsequently broke down and confessed to the crime.
- 6. Historical Landmarks in Forensic Entomology
- 7. Bernard Greenberg is regarded as the father of modern Forensic Entomology.
- 8. What do Forensic Entomologists Do? • Forensic Entomologists apply their knowledge of entomology to provide information for criminal investigations. • A forensic entomologist’s job may include: – Identification of insects at various stages of their life cycle, such as eggs, larva, and adults. – Collection and preservation of insects as evidence. – Determining an estimate for the postmortem interval or PMI using factors such as insect evidence, weather conditions, location and condition of the body, etc. – Testifying in court to explain insect-related evidence found at a crime scene.
- 9. • Flies and beetles follow a life cycle that allow scientists to estimate how long a body has been deceased.
- 10. Examples of Diptera (Flies) Flesh Fly (Sarcophagidae) Striped thorax Blow & Greenbottle Flies (Calliphoridae) Metallic thorax and abdomen House Fly (Muscidae) Cheese Skipper (Piophilidae) Early Stage Decomposition Late Stage Decomposition Life Cycle of a Calliphoridae Fly
- 11. Blue/Green bottle Flies Blow flies Family: Calliphoridae •Blowflies often are an attractive blue-green, metallic color, leading to the common English names, blue-bottles and green- bottles. •They can pick up faint traces of the odor of decay from up to 20 km away and lay their eggs in a suitable corpse. •Blow flies are one of the first insects to arrive at a cadaver– they prefer fresh, moist flesh
- 12. Life cycle of Blow fly It takes approximately 14-16 days from egg to adult depending on the temperatures and humidity levels at the location of the body.
- 13. Flesh Flies Family: Sarcophagidae • Flesh flies arrive early at a crime scene and often lay their eggs in open wounds on mammals. Adults are most common at corpses in the early stages of decomposition when the corpse is moist. Common House Flies Family name: Muscidae
- 14. Cheese Skipper Family name: Piophilidae • Cheese flies are attracted to the cheesy odor which emanates from a corpse during the later stages of decomposition ( 3 to 6 months after died), particularly when the body is undergoing butyric fermentation. • They are also common pests of cheeses. Cheese Skippers have been found in coffins buried up to 3 m deep and in corpses up to 10 years old.
- 15. Examples of Coleoptera (Beetles) Carrion Beetles (Silphidae) Adults & larvae feed on fly larvae Early to Late Stage Decomposition Late Stage Decomposition Rove Beetles (Staphylinidae) Predator of fly eggs Early Stage Decomposition Hide Beetles (Scarabidae) Usually the last to arrive Clown Beetles (Histeridae) Predator of fly eggs Ham & Checkered Beetles (Cleridae) Predator of flies & beetles; also feed on dead tissue Skin Beetles (Dermestidae) Feed on dried skin & tissues
- 16. Carrion Beetles Family name: Silphildae • The first beetles arrive at a corpse soon after the body begins to putrefy. • In contrast to the flies, beetles have chewing mouthparts and can manage tougher foods than the semi-liquid material. • The early arrivals tend to be predatory adults that feed on fly larvae. • There are over 200 species in this family, but the ones that eat dead flesh are those that belong to the subfamily Necrophorinae.
- 17. Rove Beetles Family name: Staphylinidae They eat the fauna residing on and in a corpse. Adults are early visitors to a corpse and they feed on larvae and eggs of all species of fly. Hide Beetles Family name: Dermistidae Late-arriving species tend to be specialist scavengers which feed on tougher parts like skin and tendons as the body dries out.
- 18. Determination of PMI • PMI means Postmortem Interval (the time between death and the discovery of the body). • Determination of PMI is based on two major principles: 1. SUCCESSION 2. LIFE CYCLE OF FLY
- 19. Calculating PMI from Accumulated Degree Hours (ADH) From To Temp Hours ADH Total Egg 1st Instar 70° F 23 1610 1610 1st Instar 2nd Instar 70° F 27 1890 3500 2nd Instar 3rd Instar 70° F 22 1540 5040 3rd Instar Pupa 70° F 130 9100 14140 Pupa Adult Fly 70° F 143 10010 24150
- 20. Five Stages of Decomposition Fueled by Insect Activity. • Fresh • Bloat • Decay • Post-decay • Dry (skeletal)
- 21. 1.Fresh Stage • Begins at death. Flesh flies, blow flies, ants eating fly eggs and predatory wasps. First sign of bloating due to putrefaction by anaerobic bacteria.
- 22. 2.Bloat (Days 2-7) • Swells due to gases Produced by bacteria. • Temperature rise of the corpse • Flies still present Pig carcass in the bloat stage of decomposition
- 23. 3.Decay (Days 5-13): • Gases subside, decomposition fluids seep from body. • Bacteria and maggots break through the skin. • Predatory beetles such as rove and hister beetles are attracted • Unpleasant odor • Larvae beginning to pupate. • Corpse reduced to about 20% of it’s original mass. Pig carcass in the decay stage of decomposition
- 24. 4.Post-Decay (Days 10-23): Pig carcass in the post-decay stage of decomposition Carcass reduced to hair, skin, and bones. Fly population reduced and replaced by other arthropods. Hide beetles are dominant in dry environments. Mite and predatory beetle populations increase.
- 25. 5.Dry (Skeletal) (Days 18-90): Does not always occur especially if corpse is in a wet region. Maggots will stay longer and hide beetles will not appear. In wet environments the hide beetles are replaced with reduviid insects. The corpse is reduced to at least ten percent of the original mass. In the last stage (Skeletal Stage), only bone and hair remain. Pig carcass in the dry/remains stage of decomposition
- 26. Entomotoxicology is the analysis of drugs and toxins on the development rate of carrion feeding insects. Insect tissue or remnants are collected from decomposing bodies and in their surroundings can be used as alternate specimens for toxicological analyses, when the blood, urine or internal organs are not available. In such badly decomposed bodies, fly larvae and their remnants can also be used as a credible substrate for toxicological analysis when poisoning is suspected.
- 27. Fine paintbrush for collecting eggs and Spoons for collecting maggots. Fine and medium forceps (for collecting adults and the more fragile immature insects) Hand net for catching flying insects Ethanol (70%) for storing dead specimens Protocol sheets for writing down what specimens were collected. Labels Vials and storage boxes of different sizes for preserving living and dead insects Sawdust or tissue paper for handling eggs and living larvae in vials or storage boxes Shovel and Robust plastic bags for soil samples and leaf litter Thermometer for measuring the body and ambient temperatures, as well as the larval mass temperature Camera for photographic evidence.
- 29. Significance of Forensic Entomology The presence of insects on the body that are not found in the area suggests the body was moved, and may indicate the type of area where the murder took place. If the insect cycle is disturbed, it may suggest that the killer returned to the scene of the crime. The entomologist may be able to estimate the date of death and possibly the date of the return of the killer. If maggot activity occurs away from a natural opening, this may indicate a wound. For example, maggots on the palm of the hands suggest defence wounds. If maggots feed on a body with drugs in its system, those chemicals accumulate and may be detected. If an insect is found from a specific site, it may place a suspect at the scene of a crime. If insects are found on a living individual (often young children or seniors), it may indicate neglect or abuse.
- 30. Limitations of Forensic Entomology Time of death estimates depend on accurate temperature information, but local weather patterns can be variable and data may come from stations quite distant from the crime scene. Forensic entomology relies on insect abundance. In winter, there are fewer insects and entomology's use is limited. Since it takes time to rear insects, forensic entomology cannot produce immediate results. Treatments (like freezing, burial or wrapping) that exclude insects can affect estimates.
- 31. Conclusion • Forensic entomology can make a highly effective contribution to criminal investigations, but in order for it to be of robust evidential value strict protocols should be followed with regard to collection and preservation of insect evidence, subsequent analysis and reporting. • Ideally this should be conducted by an appropriately qualified forensic entomologist or under the guidance of such.
- 32. References • Journal of forensic dental science. • B. r. Sharma, Forensic science in criminal investigation & Trials. • Dayananda, R. & J. Kiran, 2013. Entomotoxicology. International Journal of Medical Toxicological Forensic Medicine, 3(2):71-74. • Dr Dorothy Gennard - Forensic Entomology_ An Introduction-Wiley (2007)