Establishing Time of Death

1. Establishing Time of Death

2. 5 Manners of Death: • Natural Causes- illness • Suicide- take your own life • Homicide: occurs when one person is responsible for another person’s death • could be criminal = crimes with intent to kill • or non-criminal = sometimes caused by accident or self-defense • Accidental- drowning, car accident • Undetermined

3. F.Y.I • Knowing the actual or approximate time the homicide took place could offer much-needed clues to the identity of the murderer. • Identifying probable suspects and knowing where they were at the time of the homicide could pave the way for the solution of the crime. • Therefore, great care must be taken in conducting investigations to establish the time of death in a homicide.

4. 2 Estimates of Time of Death: • Police department’s official estimate • Medical Examiner’s estimate • The legal requirement is the time estimate provided should be within 4 hours accurate. 

5. Ways to Estimate Time of Death • the body temperature and the degree of cooling –algor mortis (1-1.5 degrees per hr) • the extent of stiffness -rigor mortis • the rate/location of postmortem coloration- livor mortis • Putrefaction (decay) • changes in the eyeballs – potassium levels • examining stomach contents • insect activity- the first witnesses!!

6. Algor Mortis • “Death Heat” • results in the loss of heat by a body (a general rule, beginning about an hour after death, the body loses heat by 1 to 1 1/2degrees Fahrenheit per hour until the body reaches the environmental temperature).

7. Algor Mortis (Body Temperature) • Body starts cooling about 1 hour post mortem. • The temperature of the human body usually decreases at an average 1.5 degrees per hour. • It takes the body approximately 18-36 hours to cool to the ambient temperature (temperature of surrounding environment). • Many factors can influence the cooling rate, such as: • the temperature surrounding the body, movement of air, original body temperature, body weight, body fat (a fat person takes longer time to cool off), the clothing the person wears, and the surface on which the body is lying. • After 30 hours, the body temperature begins to increase again due to decomposition. • The degree of increase depends on room or outside temperature. Weather conditions need to be determined. 

8. Rigor Mortis • “death stiffness” • results in the shortening of muscle tissue and the stiffening of body parts in the position at death (occurs within the first 24 hrs. and disappears within 36 hrs.). • Starts in the head and works its way down to the legs. • At 12 hours the body is most rigid. • Skeletal muscles cannot relax. • When you are alive, muscles release Calcium to contract. This Calcium is removed from the cells, which requires energy. In death, there is no energy, thus Calcium is not removed and the muscles remain contracted. • After 12 hours, the muscle cells begin to dissolve by autolysis

9. Rigor Mortis • The muscles live a short time even after the brain dies by using oxygen left in the body. When this O2 is gone, the muscles start to die causing the muscles fibers to get stuck together which leads to the stiffening effect called rigor mortis. • In rigor mortis, the body is limp until about 3-5 hours after death then hardness begins to set in. • The following processes occur: • stiffness in jaw — 6 hours after death • stiffness in upper body — 12 hours after death • stiffness in whole body — 18 hours after death • limpness returns to body — 36 hours after death

10. Factors that affect rate of rigor mortis • Environmental temperature – cooler, slower • A person’s weight – Body fat stores extra oxygen (therefore more energy is available after death) • Type of clothing – Clothing keeps the body warm • Illness – fever vs. hypothermia • Level of activity before death – high activity, faster • Sun exposure – Direct sunlight, warmer, faster

11. Livor Mortis • “Death Color” • results in the settling of blood in areas of the body closest to the ground (begins within 2 hours after death and continues up to 12 hrs.). • Red Blood cells break down, spilling out hemoglobin. This turns purple, outside of the cell. This is visible where the blood pools. • “Lividity” – pooling of the blood. Discoloration is permanent after 8 hours. • Environmental factors affect the rate

12. Livor Mortis (Lividity) • Literally means “the color of death” • When the heart stops, blood pressure falls down to zero. • Due to the effect of gravity, the blood then slowly settles or pools in the lowest-lying parts of the body. • The first signs are evident when the skin turns pale on the upper portions of the body, and a dark-red color is noticeable in the lowest-laying portions of the body. • Begins within one half hour after death. Maximum lividity occurs within 10 to 12 hours. • If the body is moved from its original location, you can tell by the lividity marks found in other places and not in the usual lowest point of gravity where the body is found.

13. Putrification • The process of decaying is influenced by the environment. • Decomposition starts in 30 hours and proceeds quickly after 48 hours. • 2 weeks post mortem: Bloating of the abdomen due to build up of gases from microorganisms

14. Changes in the Eyes • W/in 15 minutes: eyes become dry if open • After 12 hours, eyes turn cloudy • Potassium levels in vitreous humor (fluid inside eye) can be measured at various rates. Levels increase post mortem.

15. Stomach Contents • An examination of the stomach contents may help determine the approximate time of death. • Food eaten in the last 2 hours is not digested and remains in the stomach • Food remains in the small intestine for approximately 6 hours and 12 hours in the large intestine. • Some factors may affect the speed of food processing in the stomach: • kind of food eaten • person’s rate of metabolism • use of drugs or medication • exercise • the emotional state of the person before death

16. Insect Activity • Flies know as the blow fly (Calliphoridae) live in North America. These flies are of particular interest in homicide cases because they lay eggs on the dead bodies of humans. • The medical examiner can submit them to a entomologist, to determine their age.  • These insects provide scientists, particularly forensic entomologist, the means to establish the time of death by locating the largest (oldest maggot) inhabiting the body then measuring it in millimeters and add the number two (2) to get the estimated number of days since death.

17. There is a higher chance to solve a homicide case if it is discovered soon after the murder takes place. With homicides, if no arrest is made within 72 hours the chances of solving the crime decreases (Morn 2000). It is not a requirement to find the body to start a homicide investigation. F.Y.I.

18. The 26 Stages of Death • At the Time of Death: • The heart ceases to function • The skin becomes taut and turns grey • Muscles begin to relax • Bladder and bowels empty • Body temperature falls • After 30 Minutes: • The skin becomes purple and pale • The lips, finger and toe nails turn pale color as blood stops circulating. • Livor Mortis or lividity occurs • The hands and feet change color to blue • The eyes sink closer to the skull

19. The 26 Stages of Death • After 4 Hours: • Rigor mortis starts and turns the muscles rigid for 24 hours, then the body will turn limp. • Lividity continues • After 12 Hours: • Complete rigor mortis. • After 24 Hours: • The body takes on the ambient temperature (that of surroundings) • Semen dies for men • The head and neck turn greenish-blue • The rest of the body takes on greenish-blue hue • Odor similar to rotting meat becomes overpowering

20. The 26 Stages of Death • After 3 Days: • The gases in the body tissues creates large blisters on the skin • The whole body begins to bloat • Fluids comes out from the mouth, nose, eyes, ears, rectum and urinary opening • After 3 Weeks: • The skin, hair, and nails are loose • The skin cracks and bursts open in many places because of the pressure of internal gases and the breakdown of the skin itself • Decomposition continues until only the skeleton remains. • Teeth remain even for centuries because the enamel is the strongest material in the body. • The jawbone will also most likely remain.