Determining the Time of Death (TOD)

Slides:



Advertisements
Similar presentations
Entomology is the Study of Insects Insect Biology  Insects are the most diverse and abundant forms of life on earth.  There are over a million described.
Advertisements

STAGES OF DECOMPOSITION
The Murder Scene: Death & Autopsies
Forensic Entomology 1. 2 You will understand: The stages of death. The role insects play in the decomposition of carrion. Postmortem interval and how.
Decomposition of Human Body This ppt contains graphic images. I put pictures on slides that do not contain information so feel free to avert your eyes.
Forensic Entomology.
Forensic Entomology Notes on page 79. What is Forensic Entomology?  Applying the study of insect life cycle to estimating time of death  Flies and beetles.
Forensic Entomology Adapted and modified by Andrea Taktak for High School Forensics Forensic Entomology Adapted and modified by Andrea Taktak for High.
Estimating Post Mortem Interval (PMI)
Forensic Entomology 1. 2 You will understand: The stages of death. The role insects play in the decomposition of carrion. Postmortem interval and how.
Determining the manner and time of death Unit 2. Carl linnaeus Developed TAXONOMY SYSTEM – Classification of things in an orderly way that indicates natural.
T. Trimpe Warning: Some material in this presentation and related videos may be too graphic for some people.
Time of Death.
T. Trimpe Presentation developed for use with the Crime Solving Insects activity available at
Forensic Entomology. What is it? The use of insect knowledge in the investigation of crimes or civil disputes.
FORENSIC ENTOMOLOGY “When one biological clock stops, others begin.”
How do insects determine PMI?
T. Trimpe Warning: Some material in this presentation and related videos may be too graphic for some people.
Maggots and Time of Death Estimation
Ch. 13 Entomology.
Forensic Entomology STEM.
E NTOMOLOGY. A part from bacteria and fungi, insects are the most important processors of dead animal and human remains Insects utilize decomposing tissues.
Forensic Science Unit 4 Entomology. What is Forensic Entomology? Entomology is the study of insects. Insects arrive at a decomposing body in a particular.
Forensic Entomology Study of insects and their relation to legal issues.
1. 2 Entomology Review: Forensic entomologists study Based on the life cycle stage of insects, entomologists can determine how long a body has been dead;
Forensic Entomology. What is Forensic Entomology? Application of insects to legal issues. Insects associated with crimes Usually violent crimes such as.
Copyright © 2013 Crosscutting Concepts, LLC. All Rights Reserved. Forensic Entomology.
Initial Decay: 0-3 Days. Bacteria digest intestine then break out to surrounding organs Body’s enzymes assist with decomposition Blowflies & house flies.
T. Trimpe Warning: Some material in this presentation and related videos may be too graphic for some people.
Ch. 13 Entomology. Taxonomy Classification of Things in an Orderly Way.
Insects & Death Determining time of death through forensic entomology.
STAGES OF DECOMPOSITION
Time of Death.
TRUE OR FALSE? When a body begins to decompose the reason is smells bad is because of the blood inside the body breaking down. This is why embalmed bodies.
Maggots and Time of Death Estimation
Forensic Entomology.
Forensic Entomology Insects as Evidence
STAGES OF DECOMPOSITION
What are the stages of decomposition?
Forensic Entomology Insects as Evidence
All rights Reserved Cengage/NGL/South-Western © 2016.
Forensic Entomology Defined: The use of the insects, and their arthropod relatives that inhabit decomposing remains to aid legal investigations. 3 Broad.
9/20/2018 FORENSIC ENTOMOLOGY.
Forensic Entomology Insects as evidence.
Forensic Entomology Insects as Evidence
Forensic Entomology Insects as Evidence
Body Decomposition Watch me! April
Forensic Entomology Insects as Evidence
Forensic Entomology Insects as Evidence
Forensic Entomology Insects as Evidence
Warm Up Think back to the episode of crime 360 that featured the body found in the sewer. What did scientists do/use to figure out how long the body had.
Insect Succession.
Forensic Entomology Insects as Evidence
WARM UP #3 3/30 Settling of blood after death
Time of death Jan 2019.
Information taken from
Forensic Entomology Insects as Evidence
Forensic Entomology Insects as Evidence
Forensic Entomology Insects as Evidence
Forensic Entomology Insects as Evidence
Forensic Entomology Insects as Evidence
Forensic Entomology Insects as Evidence
Time of death Jan 2019.
Forensic Entomology Insects as Evidence
Forensic Entomology Insects as Evidence
Forensic Entomology Insects as Evidence
Entomology Chapter 12.
Forensic Entomology Insects as Evidence
Forensic Entomology Insects as Evidence
Presentation transcript:

Determining the Time of Death (TOD)

Maggots and Murder

Forensic Entomology Using the developmental stages of insects to determine TOD Larvae Pupae Eggs Adult Adult

Forensic Entomology The study of insects in relation to a criminal investigation. Insects arrive at a decomposing body in a particular order and then complete their life cycle based on the surrounding temperature. By collecting and studying the types of insects found on a body, a forensic entomologist can predict the time of death. “When one biological clock stops, others begin.” --Neal Haskell, reknown forensic entomologist

Determining the Time of Death (TOD) Using Forensic Entomology

Stages of Decomposition Initial Decay-Although body shortly after death appears fresh from outside-bacteria in body’s intestine before death begin to digest intestine itself. Autolysis-bacteria exit intestine and digest internal organs. The body's own digestive enzymes spread throughout body Enzymes inside cells-released when cell dies-break down cell and connections with other cells Flies are immediately attracted to dead bodies Without normal defense of living animal- blowflies and house flies lay eggs around wounds and body openings Eggs hatch and move into body within 24 hours. Life cycle of a fly from egg to maggot to fly-2-3e weeks

Stages of Decomposition 2. Putrefaction-4-10 days after death Putrefaction-destruction of soft tissues by of micro-organisms-results in catabolism of tissue into gases and liquids First visible sign-formation of sulfhaemoglobin in settled blood. Releasing fluids into body cavities-anaerobic respiration - produce hydrogen sulphide, methane, cadaverine, putrescine, butyric and propionic fatty acids Distention of gut-Gas build up from multiplying bacteria-internal pressure-inflates body and forces fluids from cells and blood vessels into body cavity Rate of decay increases-blowflies, flesh flies, beetles and mites Late-arriving insects-predators-feed on maggots and flesh -Maggot masses

One day old dead pig showing signs of skin changes and bloating.

Stages of Decomposition 3. Black Putrefaction-11-20 days after death Bloated body collapses-creamy flesh-exposed parts are black in color and very strong smell of decay. Body fluids drain from body and seep into soil Insects consume most of the flesh and body temperature increases with activity. Bacterial decay important-bacteria consume body if insects are excluded Several generations of maggots-migrate from body and bury in soil to pupate Predatory maggots are much more abundant Pioneer flies cease to be attracted to corpse. Predatory beetles lay their eggs in the corpse and their larvae then hatch out and feed on flesh

One week old pig-larva develop & migrate from body to pupate

Butyric Fermentation 20-50 days after death Dessication of corpse-remaining flesh is removed and butyric acid released The surface of body in contact with ground becomes covered with mold as body ferments. Beetle larva and adults feed on skin and ligaments. Predators and parasitic wasps and beetles

Dry Decay 50-365 days after death Body is dry and decays slowly-Eventually leaving only skeleton Diagenesis-process that changes skeleton’s proportions of organic (collagen) and inorganic components (hydroxyapatite, calcium, magnesium)

PMI--Postmortem Interval PMI-amount of time b/w TOD and body’s discovery Estimation of PMI- set minimal and maximal PMI Minimal PMI -determined by estimating age of developing immature insects collected when corpse is discovered Maximum PMI-determined from species of insects present and weather conditions needed for the activity of these species

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. Taking temperature of the maggot mass can find it as high as 125 degrees F.

Forensic Entomology Using developmental stages of insects to determine TOD Larvae Pupae Eggs Adult Adult

Forensic Entomology The study of insects in relation to a criminal investigation Insects arrive at decomposing body in a sequence and complete their life cycle based on surrounding temperature Forensic entomologist can predict the time of death

Metamorphosis Complete metamorphosis (holometabolous) -development from egg to larva to pupa to adult The white crust in the picture are the fly eggs.

Larva Larva hatch from the eggs and increase in size by growth steps called instars. Larva migrate from corpse and develop into an inactive pupal stage During this time, the adult insect develops internally. Two larval instars.

The Blowfly Acts as both necrophages and as predator One of the most common species on dead bodies Often arrive within 10 minutes Feed on blood and lays eggs in body cavities If food source is exhausted- will prey on other species in same genus (Chrysomya)

Maggots (fly larvae) are remarkable eating machines Posterior spiracles Spiracles are used for breathing-posterior spiracles-means that maggots can breath & feed 24 hrs a day

First instar Third Instar Second instar

Pupal Stages of House Fly

Types of Insect Collections Collection are done in three ways: Aerial Hand Live Sampling

Aerial Collection Use a net in figure 8 motion over cadaver Collect flies and put them in ethyl acetate After a few seconds-put flies into 75% ethyl alcohol-label date, time, case #, location, sample type and collector.

Live Sampling “Maggot Motels” Collect 10 to 15 live maggots of varying sizes into a rearing chamber Allow to develop into pupae and then into adults.

Hand Collection Collect maggots with forceps Put in boiling water to stretch them out and fix them Put maggots into ethanol with a label containing date, time, case #, location and collector

First instar Third Instar Second instar

Maggots can consume 60 per cent of a corpse in less than a week Maggots can consume 60 per cent of a corpse in less than a week. Video footage: R. Major Windows Media (77kb) Quicktime (275kb)

Burying Beetles

Hister Beetle

Forensic Flies