Estimating the Time Of Death in Practical Homicide Investigations
Article by Vernon J. Geberth, M.S., M.P.S.
Homocide and Forensic Consultant
©2006 Vernon J. Geberth,, Practical Homicide Investigation
Reprint: Law and Order Magazine , Vol. 55, No. 3, March, 2007
Article Expanded for Research
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Time is one of the most important factors of consideration in a murder case. It may very well convict a murderer, break an alibi, or eliminate a suspect. If the circumstances surrounding death indicate the possibility of homicide, then both the body and immediate surrounding area become crucial in estimating time of death. Estimating the time of death, especially in cases where there are no witnesses, is critical to the investigation.
Time may focus attention on various suspects. For example, the deceased may have had an appointment with someone at a specific time. Or, in cases of "exclusive opportunity" (where only certain persons are present during a specific time, e.g., husband and wife during the evening) if one of those persons is found in nightclothes the following afternoon dead from a beating, and the estimation of time of death places the incident in the range of 3 A.M. to 6 A.M., the spouse is sure to be the suspect.
A definite time of death can corroborate or disprove a suspect's alibi. Those circumstances are extremely rare e.g. a bullet hitting and stopping a watch or an eyewitness who was present when death occurred and noted the time.
In civil matters, time may be the factor that determines whether or not an insurance policy was in effect or was void. Most insurance companies include "suicide clauses" in their policies whereby they are released from contract to pay if the insured commits suicide within a specific time, usually within one year after becoming insured. Furthermore, in probating a will, it can be crucial to learn whether the husband or wife died first, since the estate usually goes to the one who expired last.
Throughout the years, forensic scientists and pathologists have searched for a definitive method of determining time of death, yet at present there is no single reliable method. Moreover, it is impossible to fix the exact time of death; hence, we refer to an estimated time. Based on an appreciation of a large number of variables, an experienced pathologist can arrive at a reasonable estimation of time of death; usually placing it within a range of hours. The process is subject to error, especially if some crucial piece of information is omitted. It should be noted, however, that this estimation certainly represents more than just an educated guess. It is a scientifically derived opinion based on a totality of specific factors distinctive to each particular case compared with ordinary time factors attributed to the pathological changes that occur in a human body.
Although the homicide investigator is not expected to have the knowledge of a forensic pathologist, he would certainly do well to have some basic understanding of the postmortem changes that occur in the human body and the effect of time and atmosphere on the cadaver, on blood pools, and on stains, so that he can make intelligent observations at the scene.
I have found that it is good procedure to take notes of the appearance of the deceased and any blood at the scene so that you can relate to the medical examiner exactly what you observed. The investigator should also interview the first officers for their observations of the scene along with the exact time of their arrival. These observations will be helpful in the analysis of approximate time of death when coupled with the results of the medical examination and autopsy. Generally speaking, the sooner after death a body is found, the more accurate and precise the estimation of time of death. A "fresh" body gives a better time-frame than one which is in advanced putrefaction.
However, it is utterly impossible to fix the exact hour and minute that life ceased unless you were there at the moment of death. That is the reason why I stress the importance of assessing and documenting the early postmortem interval changes at the scene.
The Process of Dying
To understand what takes place in the body after death, one must first have some basic knowledge of the processes that occur in the living body. During life, the systems of the human body have the capacity to maintain themselves by providing oxygen to all the body tissues. In addition, the system provides for the removal of waste products that result from body functions. This is accomplished by the circulation of blood through the arteries and veins. The heart keeps the supply of oxygen continually flowing by its pumping action. As the blood deposits oxygen to the tissues, it picks up the waste products and returns to the lungs where a new supply of oxygen is obtained. During this process, the body is able to defend itself from bacteria and germs within the body. Upon death, however, these bacteria grow at will and begin to release enzymes, which dissolve the internal body components. The changes that occur in the dead body are recognized as postmortem decomposition.
Dying is a process, and estimating the time of death depends on those factors that occur during that process. Death can be said to occur in stages, and a "smart" medical examiner will want to see the scene or have proper documentation of the scene before he or she attempts to make any determination about the time of death.
Body Changes After Death
Color. Upon death the heart ceases to function. As a result, the blood and its life-giving properties cease to circulate through the body. As the blood settles into the dependent capillaries of the lower portions of the body, it gives the upper surfaces of the skin a waxy or translucent look. The lips and nails lose their normal pinkish or life-like color.
Eyes. The eyes, which are the most sensitive area of the human body, do not react to light, touch, or pressure in death. The cornea or clear part of the eye becomes slightly milky or cloudy within a half-hour to several hours after death.
Loss of body heat. During life the body maintains an approximate temperature of 98.6° F. After death, the body gives off heat until it becomes the same temperature as the surrounding medium. The rate of cooling can be an important measurement in the estimation of time of death and is dependent upon a number of factors. The temperature at the time of death, the temperature of the environment, body covering and clothing and the portion of the body in contact with the surface area. Never take the temperature by inserting a thermometer into a wound. If a thermometer or probe is carelessly inserted into the wound, it will probably cause additional damage to the organs or tissues beneath the wound entrance or destroy or distort the wound track.
From a practical viewpoint, there are "just too damn many" variables that affect the rate of cooling, such as size and amount of fat on the body, clothing, the position of the body (bent upon itself or lying flat on surface), age of the victim, drafts, environmental humidity, etc. - that it is almost impossible to calculate them all. I recommend to investigators who want to get a rough idea of just how long the body has been dead that they place the palm of their hands on a protected surface of the body, such as under the arms. If the body is warm, death occurred a few hours ago; if the body is cold and clammy, death occurred anywhere between 18 and 24 hours ago.
Rigor mortis. The process of rigor mortis is the result of a stiffening or contraction of the body muscles related to chemical changes occurring within the muscles after death. As a general rule, rigor mortis begins 2 to 4 hours after death. Contrary to popular belief, rigor mortis starts at the same time throughout the entire body; however, it is first observed in the jaws and neck. It then seems to progress in a head-to-foot direction and is complete in 8 to 12 hours after death. At this stage, the jaws, neck, torso, and upper and lower extremities are literally "stiff as a board" and, in this marked state of stiffening, resist any change in position. Rigor "fixes" the body in the position assumed at death. Practically speaking, if the underarms are warm to touch and the body is without rigor, death probably occurred less than 3 hours earlier.
Cadaveric spasm. Under certain conditions the stiffening of the hands or arms may take place immediately at the time of death. This is known as cadaveric spasm and is often confused with rigor mortis. It is not uncommon for persons who had a firearm or a knife in their hand at the time of death to clutch it tightly in their hands after death. Also, suicides have been known to have the weapon clutched tightly in their hands after death. It is important from the investigator's point of view to note such clutching of weapons, since you can be sure that the person held this weapon at the time of his or her death
Postmortem lividity. Also known as livor mortis, this is caused by the pooling and settling of blood within the blood vessels from the effect of gravity. It appears as a purple discoloration of the skin. During life, the pumping action of the heart maintains a constant flow of blood through the numerous vessels of the body. Upon death, this pumping action ceases, and the blood pools within the dependent portions of the body. The location of livor mortis is determined by the position of the body after death. If the body is lying face down, livor will develop on the front of the body rather than on the back. The observation of lividity is important for two reasons:
For example, if lividity is observed on the back of the body found lying face down, you can be sure that the body had originally been on its back. Lividity begins about 30 minutes after death with full development after 3 to 4 hours and becomes "fixed" in 8 to 10 hours. Fixed means that the livor has settled in one position for more than 8 hours and can no longer be significantly shifted by changing the position of the body. However, parts of the body that remain in direct contact with an object, such as the floor, a piece of pipe or wood, or even the weapon, will remain white, as the pressure will not allow the blood to settle into the dependent capillaries.
- It gives the investigator a general idea how long the body has been dead;
- It tells you definitely whether or not the body was moved after death.
The investigator should know that the discoloration will not be the same for all types of death. For instance, a person whose death was caused by inhalation of carbon monoxide or cyanide or whose death occurred under extremely cold conditions will have a livor mortis, which is cherry-red in color. If a person lost a great deal of blood, there will be little or no discoloration; or in cases where death was caused due to heart failure or asphyxia, there will be a deep purple color. These observations should be recorded and the coloration of the lividity evaluated with the later toxicological examination performed at autopsy.
Remember, you are dealing with tricky circumstances, and even the experienced pathologist will have to weigh all the facts before he attempts an estimate.
Gastrointestinal tract contents. Although commonly referred to as stomach contents, this also includes digested and undigested matter within the entire body. The presence of food particles in the stomach and upper small intestine provides still another source of information to the pathologist regarding time of death. From an investigator's point of view, the presence of food on the table may offer some assistance if the victim maintained a routine eating time. When and what the deceased ate for his last meal is important information for the pathologist who will do the autopsy.
Various ingested food materials remain within the stomach for variable periods of time, depending on the nature and size of the meal. It has been determined through extensive research that under ordinary circumstances the stomach empties its contents four to 6 hours after a meal. If the stomach, at autopsy, is found to be filled with food, and digestion of the contents not extensive, it is reasonable to assume that death followed shortly after the meal. If the stomach is entirely empty, death probably took place at least 4 to 6 hours after the last meal. If the small intestine is also empty, the probability is that death took place at least 12 or more hours after the last meal. In certain cases the medical examiner will be able to determine the type of food, which still remains in the stomach, if matched with the last known meal. This can help establish a time period.
Putrefaction. The most certain sign of death is when the body is in decomposition. Decomposition, or putrefaction is a combination of two processes: autolysis and bacterial action. Autolysis is the breakdown of cells and organs through an aseptic chemical process caused by intracellular enzymes. Since it is chemical process it is accelerated by heat, slowed down by cold and stopped by freezing. Bacterial action results in the conversion of soft tissues in the body to liquids and gases. The chemicals produced as a result of putrefaction are cadaverine, butyl mercaptides as well as hydrogen sulfide and other sulfides, which generate a horrible smell.
The discoloration is a dark greenish combination of colors and is generally pronounced within 36 hours. As a result, the body begins to swell from the putrefactive gases emitting an extremely repugnant odor. The rate of decomposition depends on the temperature, ground conditions, amount of clothing, size of the body, etc
This particular method of determining time of death is very inaccurate because of the variables involved. The putrefactive changes disfigure the facial features making visual identification by relatives impossible. Postmortem changes may also alter the appearance of and may camouflage antemortem injuries. When bloating and darkening occurs it may be difficult to determine the race and color of the deceased. The general signs of putrefaction are:
1. Greenish discoloration of abdomen and genitals. 2. Veins in skin blue or purplish due to pigment of decomposing blood. (This is referred to as marbling.) Marbling is produced by the hemolysis of blood vessels with reaction of hemoglobin and hydrogen sulfides and development of red, purple, or greenish black discoloration along the vessels.
3. After the body fluid dries, a yellow parchment-like membrane forms. 4. After several days: a. Abdomen swells, body bloats (from gas).
b. Purge fluid emits from mouth and nose (the source being the lungs and stomach).
c. Rectum may empty.
d. Skin blisters, resembling peeling sunburn, filled with watery fluid and putrefactive gases appear on the skin, which has darke
Adipocere. This is a greasy, soaplike substance, which develops on the surface of a body that has been lying in a moist area such as a swamp or in damp soil. It is due to chemical changes that occur in the body fats - hydrogenation of body fats into fatty acids.
Mummification. The conditions that produce mummification are the exact opposite of those which cause adipocere. If death occurs in a hot dry place with an adequate and constant circulation of dry air, and body fluids are rapidly absorbed, the body tissues become hard and dry instead of decomposing. The mummification process delays putrefaction, and as a result the form of the body may be preserved for years.
Information Derived from the Scene
Information obtained by the investigator relative to events associated with the deceased is of utmost importance. This is where the work of the homicide detective really comes into play. I have been personally involved in many homicide investigations where the determination of the approximate time of death was directly related to the information retrieved from the crime scene and the neighborhood canvass.
The date and time the deceased was last seen alive gives the detective a starting point to begin the task of narrowing the time of death. The status of the deceased's home or apartment lends additional information - e.g., are there any current newspapers, milk deliveries, mail in the mailbox, dishes in the sink, food on the table, etc.? Are the electric lights on or off? If the lights are burned out, is the light switch in an on or off position? Are the shades drawn or open?
The detective will want to reconstruct the deceased's last known movements. These would include who spoke to him or her last and where the deceased was prior to being found (at home, at work, with a friend, etc.). The failure of the deceased to perform a daily routine, such as picking up the newspaper, reporting for work, jogging, calling friends or family, or any other personal habit which was routine in his or her life, will also help narrow the time frame.
In cases where there has been a struggle and the deceased has a broken watch, or there is a clock in the room that has been damaged, causing it to stop, the time of death can be pinpointed if the investigator can ascertain if the timepiece was in working order prior to death, and if it kept correct time.
Remember, the presence of prepared food on the table may offer assistance in determining time of death if the investigator can ascertain that the victim maintained a routine eating time.
Information derived from the scene as well as knowledge of any personal habits of the deceased will play an important part in the final estimate of time of death. These are referred to as associative factors.
The estimate of time of death is complex. Before you lock yourself into a specific time frame, it is imperative that all the information available be examined by competent experts. If the time of death tends to fix responsibility for the death, or becomes the factor that points the finger at a particular suspect, then the estimate must be based on positive facts and interpreted by the experienced pathologist.
The physical manifestations of death discussed in this article, as well as the autopsy findings, the deceased's personal habits, the medical opinion regarding survival interval, the period between the infliction of injury and death, and the statements of witnesses must be taken into consideration in the final analysis.
Therefore, complete cooperation between the experienced homicide investigator and the medical examiner/coroner is essential if there is to be an intelligent estimate of time of death.
Vernon J. Geberth, M.S., M.P.S., retired from the NYPD Homicide Division with the rank of Lieutenant Commander. He may be reached at www.practicalhomicide.com. These copyrighted materials have been excerpted with permission of the author from Practical Homicide Investigation: Tactics, Procedures, and Forensic Techniques. CRC Press, LLC. Article Has Been Expanded for Research.
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