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Forensic Science: Fundamentals & Investigations, Chapter 11 2

Chapter 11 Death: Manner, Mechanism, Cause, and Time By the end of this chapter you will be able to:

explain the development of livor, rigor, and algor mortis following death

use evidence of these to estimate time of death use evidence on stomach contents to estimate

time of death use insect evidence to estimate time of death explain how environmental factors can affect the

estimated time of death All Rights Reserved South-Western / Cengage Learning © 2009


Death Death

The Manner of Death The manner of death can be ___________,

_____________, _____________, ____________, or _____________.

Sometimes it is _____________ to determine the manner of death.

The _____________________ manner of death is ______________.


Death Death

Cause and Mechanism of Death

The reason for the death is the cause of the death.

The ______________in the body that brought about the _______________ is the mechanism of death.


Time of Death—Livor Mortis

The Leaden-Color of Death When red blood cells break down, they turn a

____________________. With decomposition, blood ____________ and

settles in the ______________ of a body. The _________________ that accompanies

this becomes permanent after ____ hours. _________________ accelerates the process.


Time of Death—Rigor Mortis

The Rigidity of Death At death, skeletal muscles ____________ relax. ____________________, _______________ in

these muscles. The muscles become ____________. This starts in the ________ and works its way

down to the _______. After about ___ hours, the muscle fibers begin to

_____________, and ______________ begins.



At _____hours after death, the body is at its _____ rigid state.

If a body has ____ visible signs of rigor, it probably has been dead _____ than __ hours or ____ than ___.

If the body exhibits rigor ____ in the ____ and ____, the time of death is just over ___ hours.

This ________ will have disappeared for the most part after ___ hours.



Many factors affect when rigor mortis sets in and how long it lasts:

– ________________________– ________________________– ________________________– ________________________– ________________________– ________________________


Time of Death—Algor Mortis

The Chill of Death In death a body no longer generates _______

and begins to ________ down. To find the _________ temperature of a corpse, a

thermometer is inserted into the _______. Body heat is lost at about __ to ___ degrees an

______. Time of death determined by temperature

calculations is expressed as a ______________.


Time of Death—Stomach and Intestinal Contents

Based on these specifics, give an estimate for each of these on how much time has passed since the meal was eaten: 1. _________________________________2. _________________________________3. _________________________________


Time of Death—Stages of Decomposition

Choose: A. Within 2 days. B. After 4 days. C. Within 6-10 days.

1. Fluids begin to leak from body openings as cell membranes rupture.

2. Discoloration of the face.

3. The skin sloughs off.

4. The skin blisters.

5. Green and purplish staining from blood decomposition.

6. The corpse bloats.

7. Eyeballs and other tissues liquefy.

8. The abdomen swells.

9. Marbling appearance on the skin.


Time of Death—Insects

Besides recording data about the environment at a crime scene, a __________________collects insect evidence.

Within _____________ of a death, certain insects arrive to lay their eggs on the warm body. ___________ are a common example.

As a corpse progresses through the stages of decomposition, other kinds of insects arrive.



1. _____________ can be found in the ______, _____ areas of a corpse within ___ hours after death.

2. They will have progressed to the ____ of their ___ larva stages (illustration of one shown above) within _______ hours.

3. By the ____ or _____ day they will have progressed to the ____ of their 3 larva stages.



4. By the ___ or ____ day the larvae will migrate away from the corpse to a _____ place.

5. Becoming ____ and immobile within _____ days, they will change from white to dark brown.

6. By the ____-____ day the pupa cases will split open and _________________ (illustration of one shown above) will emerge.



Because scientists ________ how long it takes for the various stages of development at given temperatures, forensics entomologists can _______ when the insects arrived.

Because life cycles are affected by fluctuations in the daily ____________ conditions, ____________ _______ provide an exact time of death.

Insect evidence, nonetheless, can yield a close ______________.

What do they do?_____________________apply their knowledge of entomology to provide information for criminal investigations.

A forensic entomologist’s job may include:

• Identification of _________ at various stages of their life cycle, such as eggs, larva, and adults.

• ______________ and ___________ of insects as evidence.

• Determining an estimate for the ____________________or _____ (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.

• _____________ in court to explain insect-related evidence found at a crime scene.

Did you know? Maggots can be used to test a corpse for the presence of poisons or drugs. Some drugs can speed up or slow down the insect’s development.

Cool Jobs: Forensic EntomologyDiscovery Video

The broad field of forensic entomology is commonly broken down into three general areas: _______________, _________, and ______________________________.

The medicolegal section focuses on the _______________ of the legal system and deals with the ___________ (or carrion) feeding insects that typically infest human remains.

The urban aspect deals with the insects that __________ and his _________ environment.

How diverse is forensic entomology?

• The diverse applications of forensic entomology include the detection of ___________ and ___________________.

• Published cases exist that detail parents intentionally using wasps and bees to sting their children as a form of _________________.

• Additionally, entomological evidence has been used to prove ____________________ for wounds existing on the elderly under both private and institutional care.

• It is theorized that the _________ (or mere ________) of bees and wasps may be responsible for a __________ number of __________occupant car accidents that seem to lack a definitive cause.

• Some accident studies have shown insects to be within the top _____ causes of automobile accidents.

• In addition to automobile accidents, insects have been suspected of causing ______ crashes through the _________ of essential instrumentation, and even implicated in the obstruction of ___________ causing engine failure.

• Forensic entomologists are also requested to examine the ________________of insects that have impacted and lodged on the ______________, ____________, and ______________ of automobiles.

• Analysis of such remains can yield evidence to the ____________ path of an automobile through particular areas when pinpointing the location and areas of travel are of unique importance.

• Insects can also _______ the ____________ of blood spatter pattern analysis.

• Roaches __________________ through pooled and splattered blood will produce tracking that may not be readily recognizable to the untrained observer.

• Similarly, flies and fleas may also track through pooled and spattered blood. However, flies will also feed on the blood and then pass the partially digested blood in its feces, which are known as “____________________________".

If a crime occurs in a _______________________apartment, fecal drops already present would serve to confuse analysts as those droplets would test positive for human blood.

Therefore it is important to recognize and __________________ the natural artifacts that may occur from the presence, feeding, and defecation of roaches, flies, and fleas.

Insects that feed on living, decomposing, or dried vegetable material are submitted to the forensic entomologist in an effort to determine the ____________ or _______________.

This is particularly important with vegetative material such as _________________________.

Insects as Evidence

Forensic entomologists use their knowledge of insects and their life cycles and behaviors to give them clues about a crime.

Most insects used in investigations are in two major orders:1 – ___________(Diptera) and2 – ________________ (Coleoptera)

Blow Fly

Carrion Beetle

Images: Top Right - http://www.insectinvestigations.com/aboutfe.htm, Chart - http://www.clt.uwa.edu.au/__data/page/112507/fse07_forensic_entomology.pdf

_______________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.

______________ data is also an important tool in analyzing insect evidence from a corpse. Investigators will make note of the temperature of the air, ground surface, the interface area between the body and the ground, and the soil under the body as well as the temperature inside any maggot masses. They will also collect weather data related to daily temperature (highs/lows) and precipitation for a period of time before the body was discovered to the time the insect evidence was collected.

Other factors that might affect their PMI estimates:

1.Was the body ______________in an area or ___________ in a material that would have prevented flies from finding the corpse and laying eggs?

2.Were other _______________________ that may have affected the development of the collected species?

3.Were there _____________________________- in or on the body that might have affected the larvae’s development?

Did you know…The “Body Farm” in Knoxville, Tennessee is a university research facility to investigate human decomposition under various conditions in order to understand the factors which affect its rate. Click the image to view a

video about the Body Farm!

Image: http://www.umext.maine.edu/images/FlyLife.jpgInformation: http://www.kathyreichs.com/entomology.htm and http://www.forensicentomologist.org/

Blow Fly Metamorphosis

1st – Adult flies lay _____ on the carcass especially at wound areas or around the openings in the body such as the nose, eyes, ears, anus, etc.

2nd – Eggs hatch into ______ (maggots) in 12-24 hours.

3rd– Larvae continue to grow and______ (shed their exoskeletons) as they pass through the various instar stages. 1st Instar - 5 mm long after 1.8 days 2nd Instar - 10 mm long after 2.5 days 3rd Instar – 14-16 mm long after 4-5 days

4th – The larvae (17 mm) develop into pupa after burrowing in surrounding soil.

5th – _______ flies emerge from pupa cases after 6-8 days.

Blow flies are attracted to dead bodies and often arrive within minutes of the death of an animal. They have a ________ life cycle that consists of ___, _____, ____, and _____ stages.

It takes approximately 14-16 days from egg to adult depending on the temperatures and humidity levels at the location of the body.

Adult

EggsPupa

3rd Instar Larva

2nd Instar Larva

1st Instar Larva

Examples of Diptera (Flies)

Informational Source: http://naturalsciences.org/files/documents/csi_tg_overview.docImages: Top Left - http://www.scienceinschool.org/repository/images/issue2forensic3_large.jpg, Middle-Left: http://forensicfact.files.wordpress.com/2008/04/blowfly053.jpg, Top Right - http://users.usachoice.net/~swb/forensics/P1.jpg, Bottom - http://www.deathonline.net/decomposition/corpse_fauna/flies/index.htm

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

Examples of Coleoptera (Beetles)

Informational Source: http://naturalsciences.org/files/documents/csi_tg_overview.doc Images: http://www.cals.ncsu.edu/course/ent425/library/spotid/coleoptera/coleoptera.html & http://www.forensicflies.com/beetles.htm

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

Click the image above or click here to visit the website at http://www.pbs.org/wnet/nature/episodes/crime-scene-creatures/interactive-determine-the-time-of-death/4390/

Let’s give it a try …


. . . . . . . . . . . . . . . . . Summary. . . . . . . . . . . . . . . . . Summary

A body decomposes through the 3 changes of livor, rigor, and algor mortis.

Forensic scientists use evidence from these to estimate the time of death.

They also use stomach contents and insect evidence to estimate the time of death.

It is also important to remember how environmental factors can affect the estimated time of death.

Warning: Some material in this presentation and related videos may be too graphic for some people.

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Transcript of Warning: Some material in this presentation and related videos may be too graphic for some people.