VED PRAKASH SHARMAMFSC, 3RD

Sem.

Presented BY-

FORENSIC ENTOMOLoGY• Forensic entomology is the application and

study of insects and other arthropods biology to legal issues, especially in a court of law.

• Flies and beetles follow a life cycle that allow scientists to estimate how long a body has been deceased.

History of Forensic Entomology

• 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.

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 (the

time between death and the discovery of the body) 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.

Insects as Evidence

• Most insects used in investigations are in two major orders:

1 – Flies (Diptera) and2 – Beetles (Coleoptera)

• Species succession may also provide clues for investigators. Some species may to feed on a fresh corpse, while another species may prefer to feed on one that has been dead for two weeks. Investigators will also find other insect species that prey on the insects feeding on the corpse.

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

Five Stages of Decomposition Fueled by Insect Activity.

• Fresh

• Bloat

• Decay

• Post-decay

• Dry (skeletal)

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.

• Autolysis, the degradation of complex protein and carbohydrate molecules, occurs.

Pig carcass in the fresh stage of decomposition

2.Bloat• Swells due to gases

produced by bacteria• Temperature rise of the

corpse• Flies still present adult and

larval blowflies attracted in large numbers to seepage & soil fauna moves away due to wetness of earth; ants and other species of flies prey on maggots.Pig carcass in the bloat stage of

decomposition

3.Decay• 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

4.Post-Decay• Carcass reduced to hair, skin, and

bones.– in dry habitats - remains consist

of dry skin, cartilage and bones; site for dermestid beetles, histerids, fly pupae, immature and adult rove beetles

– in wet habitats – large quantities of wet, viscous material (byproducts of decomposition) found in soil under the remains; site for adult and immature moth flies, rove beetlesPig carcass in the post-decay stage of

decomposition

5.Dry (Skeletal)• Does not always occur especially if corpse is

in a wet region. Maggots will stay longer and hide beetles will not appear.

• The corpse is reduced to at least ten percent of the original mass.

• In the last stage (Skeletal Stage), only bone and hair remain.

• some dermestids, fly pupae, immature and adult rove beetles, normal soil fauna consisting of mites, etc. start to return; this stage could last for several months to years.

Pig carcass in the dry/remains stage of decomposition

life cycle of blow fly-

Collection of entomological evidence -

• Camera & video, to fix the evidence site.

• Net to catch fly, etc. Sticky traps are also used instead.

• Collection of paraphernalia: Live specimen containers, killed creatures container jar, forceps, spoon , small paint-brushes.

• Preservation usually 98% alcohol (ethanol) is used.

• Recording materials like labels, pencil, ruler, crime scene from , if any, prescribed by authorities.

• Gloves and hand towels are usually taken along to maintain hygiene.

FACTOR AFFECTING PMI-• Night Time & cold temperature.

• Rain.

• Physical prevent insect from reaching a corpse can delay as- Storage in sealed container or wrapping, submergence of water etc.

refrences-• Journal of forensic dental science

• B. r. sharma, Forensic science in criminal investigation & Trials

• https://en.wikipedia.org/wiki

• encyclopedia of forensic sciences three-volume set 1-3