Establishing Time of Death

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

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.

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. 

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!!

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. 

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

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.

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

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.

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

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.

F.Y.I. 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.

The 26 Stages of Death At the Time of Death: After 30 Minutes: 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

The 26 Stages of Death After 4 Hours: After 12 Hours: After 24 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

The 26 Stages of Death After 3 Days: After 3 Weeks: 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.