Time of Death

The Face of Death

"All I desire for my own burial is not to be buried alive "All I desire for my own burial is not to be buried alive." - Lord Chesterfield, 1769 17th Century Coma or weak heartbeat = DEAD and BURIED Fear of being buried alive bell in coffin “Saved by the bell” Many designs included ropes which, when pulled, would ring the church bell, or a purpose-mounted bell. Others replaced the bell with a raiseable flag, a powerful fire cracker or a pyrotechnic rocket. Some included a shovel, a ladder and a supply of food and water. An essential element, which was overlooked in some designs, was a breathing tube to provide air and occasionally even sustenance.

"Have me decently buried, but do not let my body be put into a vault in less than two days after I am dead." - deathbed request of George Washington. Waiting Mortuaries Established in 17th century Those thought to be dead…placed on cots and observed until body began to rot Now…. they’re dead

Is a person with a heartbeat alive even if there is no brain activity? What do you think?

Cessation (Death – End of Life) Somatic death Death of the entire body Legal definition: Death of upper brain & brain stem Cellular death Death confined to cells or tissues in the body Brain stem controls basic bodily functions: breathing & blood circulation A person who is brain dead has lost both the capacity to think and perceive, as well as the control of basic body functions.  “Irreversible cessation of circulation of blood.”

Lend me a looking glass; If that her breath will mist or stain the stone, Why then she lives.  Shakespeare, King Lear Death begins when the heart stops beating. Deprived of oxygen, a cascade of cellular death commences. Heart stops beating and/or lungs stop breathing. Body cells no longer receive supplies of blood and oxygen.

Autolysis When a cell dies, it breaks down Breakdown = autolysis Definition: the destruction of a cell through the action of its own enzymes Once enough cells begin autolysis, life cannot be restarted Cell membrane dissolves – enzymes and other cell contents spill – digest surrounding tissues Begins with brain cells and finishes with skin cells

Manners of Death Natural Accidental Suicidal Homicide Undetermined death results from natural disease processes Accidental Caused by unplanned events Suicidal Person purposefully kills oneself Homicide Caused by another person Undetermined Natural death: heart attacks, cancers, pneumonia, stroke: largest category of death

Categorize Manner of Death A man with a heart condition is attacked and dies from a heart attack during the assault Accident or homicide? An elderly woman dies after being kept from receiving proper health care by her son. Natural or homicide? Both cases = homicide. Proving in court that manner of death was a homicide may be difficult

Cause of Death Cause of death = reason someone dies “Proximate cause of death” – refers to an underlying cause of death… rather than FINAL cause of death Ex: If someone is exposed to large amounts of radiation and then developed cancer Proximate cause of death? Radiation exposure!

Mechanism of Death Mechanism of Death = the specific change in the body that brought about the cessation of life Ex: If cause of death is shooting, what would be the mechanism of death? Loss of blood, cessation of brain function or exsanguination (total blood loss) Ex: If cause of death is heart attack, what would be the mechanism of death? Heart stopping to beat or pulmonary arrest

Estimate Time of Death Evaluate the stage of decomposition that the body was found in Brain cells can die if deprived of oxygen for more than three minutes. Muscle cells live on for several hours. Bone and skin cells can stay alive for several days. It takes around 12 hours for a human body to be cool to the touch and 24 hours to cool to the core.

Rigor Mortis “The Rigidity of Death” In mammals Body stiffening of muscles in the position that they are in when death occurs First eyelids, neck, jaw, then other muscles (from head to toe) cells of muscle, skin, and bone live on--dying only when metabolic waste products build up, sometimes days later.

Rigor Mortis How? Aerobic respiration stops, anaerobic respiration begins Conversion of sugar to pyruvic acid to lactic acid 2 ATP anaerobic vs. 36 ATP aerobic Lack of ATP forces muscles to stay contracted Aerobic stops because circulation has stopped. Energy stops being produced, no energy to pump out calcium that has diffused in muscle cells, calcium concentration rises forces muscles to stay contracted. This occurs until muscle proteins start to decompose. Cells cease aerobic respiration, and are unable to generate the energy molecules needed to maintain normal muscle biochemistry.Calcium ions leak into muscle cells preventing muscle relaxation. Muscles stiffen and remain stiff (rigor mortis) until they begin to decompose.

Active Transport Going against the concentration gradient Requires energy (ATP) Necessary for the Ca2+ pump to relax muscles The concentration of calcium ions is higher in the fluid surrounding muscle cells than it is inside the cells, so calcium tends to diffuse into the cell. To relax, muscle cells must expel the calcium ions from the cell and this requires energy molecules to pump them across the cell membrane. After a body has died, the chemical reaction producing these energy molecules is unable to proceed because of a lack of oxygen. The cells no longer have the energy to pump calcium out of the cell and so the calcium concentration rises, forcing the muscles to remain in a contracted state. This state of muscle stiffening is known as rigor mortis and it remains until the muscle proteins start to decompose.

Fluid surrounding muscle cells Rigor Mortis Inside cell Fluid surrounding muscle cells Ca2+ naturally flow from fluid surrounding muscle cells to inside the cell To relax muscles, Ca2+ must flow back across the cell membrane Requires ATP energy, not enough ATP after death Muscles stay contracted

Rigor Mortis Timeline Begins 1-6 hours after death Maximum stiffness 12 hours after death Stiffness decreases until 36 hours after death when muscles have decomposed Depends on temperature, activity at death, illness, physical conditions where body found

Cadaveric Spasms Occurs at the moment of death Most common when person has died violently Involves a certain group of muscles hand, forearm usually involves an object tightly clutched in the hand of the victim - the suicide weapon, material from the assailant, or whatever might have been close to the victim at the time of death

Livor Mortis “Death Color” Lividity Dark purple discoloration of the skin resulting from the gravitational pooling of blood to the lowest points of the body Dependent on body position In deaths from carbon monoxide poisoning, it is classically described as "cherry red“ Onsets immediately Within about 30- 60 minutes of death the blood in most corpses, dead from natural or non-natural causes, becomes permanently incoagulable Death from exposure to cold: bright pink Cyanide poisoning: scarlet, violet Parts of body covered by moist clothing: pink Refrigeration causes body to turn from purple to pink – color dependent on skin pigment and any other chemicals in the body Body cells no longer receive supplies of blood and oxygen. Blood drains from capillaries in the upper surfaces and collects in the blood vessels in the lower surfaces. Upper surfaces of the body become pale and the lower surfaces become dark.

Livor Mortis Duality of distribution After 10-12 hours lividity becomes “fixed” If body is moved there will be a dual lividity pattern

Algor Mortis “Death Heat” “The Chill of Death” Most useful single indicator of time of death within 24 hours post mortem “Body Cooling” Estimated that the body temperature drops approximately 1.5F/hour Cooling effected by: Location, weather, clothing, activity at death, victim size

Algor Mortis To find the standard temperature of a corpse, a thermometer is inserted into the liver Why the liver? Standard location so investigators can compare results

Aqueous Humor Clear, watery fluid in the eye Can measure the amount of potassium (K+) in the aqueous humor to determine time of death K+ amounts increase for up to 104 hours after death Temperature at time of death effects K+ levels Fluid shows chemical changes immediately after death Age, sex, temperature, humidity do not effect K+ levels

Stomach Contents Shows nature of last meal & abnormalities Stomach starts to empty within 10 minutes If the victim had a… Light meal: will stay in stomach 1-2 hours Medium meal: will stay in stomach 3-4 hours Large meal: will stay in stomach 4-6 hours Emotional state effects stomach emptying Liquids digested faster than semi solids which are digested faster than solids