1.What are some things that you can look for on a corpse when determining time of death (TOD)? 2.A factor that can affect determining TOD would be Objective: You will be able to collect data in order to determine TOD warmup: `

Videos 10 Functions Working After Death 1. _______________ 6. _______________ 2. _______________ 7. _______________ 3. _______________ 8. _______________ 4. _______________ 9. _______________ 5._______________10. ______________

Locard's Exchange Principle in Forensic Science "Any action of an individual, and obviously, the violent action constituting the crime, cannot occur without leaving a trace." Edmond Locard. Any criminal leaves behind a trace when committing a violent crime. It is the investigator's duty to find this trace evidence and reconstruct the events of the crime.

Ti me of Death T.O.D. P.M.I.= Postmortem (after death) Interval

Death is divided into 2 types: 1. Somatic death – the individual is irreversibly unconscious 2. Cellular death – a. the cells quit respiration and metabolism. b. when all cells are dead, the body is dead.

Determining time of death (PMI) Factors used : a. Algor mortis b. Rigor mortis c. livor mortis

Algor Mortis – cooling of the body after death. Normal Body Temperature = 98.6 ˚F (37 ˚C) After death, the body loses heat at rate of »1.5˚F/hr until it reaches ambient temperature (T of environment). Rate will vary based on the environment. Body temperature should be taken rectally or from the liver to be most accurate.

1. obesity 2. clothing 3. warm still air 4. exposure to direct sunlight 5. enclosed environment Factors that affect algor mortis rate:

Rigor Mortis – within 15 minutes of death the body stiffens due to the accumulation of chemical waste products in the muscles. Begins in the face, neck, arms and shoulders and moves throughout the rest of the body last up to hours leaving the body after about 72 hours.

1) » 2 hours after death – stiffness detectable in the small muscles of face and neck & then it progresses down toward the toes 2) Next » 8 – 12 hours– entire body stiffens 3) Next » 18 hours – body remains fixed (rigid stage of rigor mortis) 4) After the rigid stage – process reverses itself; rigidity is lost in the order that it appeared, starting with small muscles of face After another 12 hours – muscles are relaxed again (flaccid stage of rigor mortis) Rigor mortis is only useful for estimating time of death during first hours after death. Predictable Pattern of Rigor Mortis

1. victim who ran from assailant before death 2. victims of strychnine poisoning 3. victim of any fever producing process or heat stroke In general, heat speeds up the process and cold slows it down. Not always reliable to determine time of death because the rate can be altered (outside crime scene) Things that can alter the rate of rigor mortis:

Discoloration – Livor Mortis red blood cells separate and settle to the lowest point of gravity. Caused by stagnation of blood in vessels and gravity postmortem lividity or postmortem hypostasis Lividity appears in hues of red Cherry red = Carbon Monoxide poisoning Maroon is normal

Appears » 30 minutes – 2 hrs after death Reaches its maximum 8-12 hrs after death Can change if body is moved in the first few hours, but becomes fixed after 6-8 hrs Fixing process is gradual Discoloration – Livor Mortis

If lividity appears on the front but the corpse is on it’s back = the corpse was moved PM. The lividity will “pattern”,based on if the body is lying on an object. Ex. tire iron or rocks Discoloration – Livor Mortis

Ocular Indicators- “cloudy eyes “ if the eyes remain open after death, a thin film forms on the surface. 2-3 hours up to 24 hours if the eyes were closed C oncentration of potassium within the vitreous humor (thick, jellylike substance that fills your eyeballs) increases slowly during the first few days. This process is independent of ambient temperature. Only really accurate though during first few days after death

T. Trimpe Forensic Entomology Insects as Evidence

What do they 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. Cool Jobs: Forensic Entomology Discovery Video

Entomology is the study of insects, often including spiders and other arthropods.

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 – Flies (Diptera) and 2 – Beetles (Coleoptera) Blow Fly Carrion Beetle The name comes from the way corpses swell up, causing them to become bloated, or "fly- blown".

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.

Weather 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: Was the body enclosed in an area or wrapped in a material that would have prevented flies from finding the corpse and laying eggs? Were other insect species present that may have affected the development of the collected species? Were there drugs or other poisons in or on the body that might have affected the larvae’s development? Click the image to view a video about the Body Farm!

Blow Fly Metamorphosis 1st – Adult flies lay eggs 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 larva (maggots) in hours. 3rd– Larvae continue to grow and molt (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 – mm long after 4-5 days 4th – The larvae (17 mm) develop into pupa after burrowing in surrounding soil. 5th – Adult 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 complete life cycle that consists of egg, larva, pupa, and adult stages.

It takes approximately days from egg to adult depending on the temperatures and humidity levels at the location of the body. Adult Eggs Pupa 3rd Instar Larva 2nd Instar Larva 1st Instar Larva Blowflies are poikilothermic = the rate at which they grow and develop dependent on temperature and species. Life Cycle of a Blowfly

Examples of Diptera (Flies) Flesh Fly (Sarcophagidae) S triped thorax Blow & Greenbottle Flies (Calliphoridae) M etallic thorax and abdomen House Fly (Muscidae) Cheese Skipper (Piophilidae) Early Stage Decomposition Late Stage Decomposition Life Cycle of a Calliphoridae Fly

What are Maggots?

Maggots, by definition, are fly larvae, just as caterpillars are butterfly or moth larvae.

The body is designed for sucking and slurping = the larvae are Necrophagous (corpse-eating)

Examples of Coleoptera (Beetles) Carrion Beetles (Silphidae) A dults & larvae feed on fly larvae Early to Late Stage Decomposition Late Stage Decomposition Rove Beetles ( Staphylinidae) P redator of fly eggs Early Stage Decomposition Hide Beetles ( Scarabidae) Usually the last to arrive Clown Beetles ( Histeridae) P redator of fly eggs Ham & Checkered Beetles (Cleridae) Predator of flies & beetles; also feed on dead tissue Skin Beetles (Dermestidae) Feed on dried skin & tissues

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