Methods used for the Estimation of the Time since Death - Coursework Example

Methods used for the Estimation of the Time since Death   Methods used for the Estimation of the Time since Death The accurate estimated of the postmortem interval (PMI), which is also commonly referred to as time of death, is found to be of paramount importance for not only the person’s family members, but also the police when they arrive at the scene of what they suspect to be a questionable death. Determining the precise time of death of a victim is important as it helps in narrowing down investigations to a specific time frame, as well as a narrow range of probable suspect. Fixing the time of death within probable limits is seen to be a recurring problem in forensic medicine. The longer the time between the examination of a body and a person’s time of death, the wider the general limits of probability. In the event of a long post mortem interval, it is often found that environmental evidence and not anatomical changes will play a significantly bigger part in furnishing reliable data that can be used in correctly estimating the time of death. The evidence that is used in the estimation of time of death essentially comes from three main sources. These three sources comprise of corporal evidence which is the evidence that is found in the body, Environmental and associated evidence which is the evidence that is found in the vicinity of the body, and anamnestic evidence which is evidence that is based on the deceased person’s ordinary movements, habits and day to day activities. Methods of estimating time of death: The Rate Method: This method produces estimations of time of death by evaluating the absence or presence of a number of indicators in a diseased person against the known behavior of these indicators (Pramod et al., 2014). The Concurrence Method: This method works by comparing the occurrence of different events that happen to have taken place near or at the time of death. The method also evaluates events that appear to offer crucial information that helps in suggesting a probable time period for the death event in question (Pramod et al., 2014). Estimating Time since Death Using the Rate Method There are several indicators that can be helpful in estimating time of death using the rate method, these indicators include: Rigor Mortis: Ordinarily, death is usually immediately followed by a process of total muscular relaxation which is commonly referred to as muscular flaccidity. Muscular flaccidity is in turn succeeded by rigor mortis which is a state of generalized muscular stiffening. After a largely variable time period, rigor mortis eventually passes off and is followed by secondary muscular flaccidity. The general quoted rule of thumb that is used to estimate time since death using rigor mortis is that rigor commences in about 6 hours from the time of death. The process is eventually fully established after an additional 6 hours. A body remains in this state of rigor mortis for a period of about 12 hours before it starts to pass off as the muscle fibers begin to relax through a process of autolysis. Of note however, is that rigor mortis has a number of demerits as it can severely be affected by a myriad of factors such as the degree of muscular activity that was engaged in before death and the environmental temperature. According to Jain (2004) in temperate climates rigor typically starts to disappear after a time period of about 36-48 hours after death, however in the warmer climate putrefaction may be completely displaced within 9-12 after death. Body Cooling (Algor Mortis): Algor mortis is perceived to be the single most useful indictor of time of death within a period of 24 hours of post mortem. The assessment of body cooling is based on the body’s core temperature, and this reading is normally derived from the intra-abdominal temperature. It is a matter of professional judgment whether this temperature is measured per rectum or via an abdominal stab. The use of body temperature to estimate the time of death only applies in the temperate and cool climates as there is minimal temperature fall in the tropical regions and in some of the more extreme climates, the body temperature can actually rise after death (Pramod et al., 2014). Other than climatic conditions, algor mortis is affected by a number of demerits such as immersion in water, the size of the body, climate, clothing and outer covering as well as by humidity and the movement of air (Snow 2005). Livor Mortis (Lividity): This a dark purple skin discoloration that results from the pooling of blood in the capillary beds and veins as a result of gravity which follows soon after the cessation of blood circulation in the body. Although this process begins immediately after circulation stops, it progresses at a faster rate and is more pronounced among persons dying slowly as a result of circulatory failure. While livor mortis is present in all body, it is at times inconspicuous in some others and can easily escape notice (Snow 2005). Livor mortis is able to develop under the influence of gravity because blood remains liquid and does not coagulate throughout a cadaver’s vascular system. The blood in most corpses generally becomes permanently incoagulable within a time period of about 30-60 minutes after death. Lividity in a corpse has the effect of causing it to acquire a reddish – purple or purple coloration and in the event that the body is exposed to air, it may acquire a pink color at the sides but never at the back and the other areas of the body close to the ground. Lividity becomes first apparent after about 20-30 minutes of death when dull red blotches or patches start developing. These patches coalesce and deepen in intensity over the succeeding hours to eventually form large areas of a reddish purple discoloration. Lividity tends to become fixed after about 10-12 hours and re-positioning the body will only result in the formation of a dual pattern of lividity as it is impossible for the primary distribution to completely fade out (Jain 2004). Putrefaction (Postmortem Decomposition): Putrefaction is defined as being the postmortem destruction of the body’s soft tissues due to the action of both enzymes and bacteria. Putrefaction is seen to result in the gradual dissolution of body tissues into salts, gases and liquid. During the process, the main changes that can be recognized are the evolution of gases, changes in the color of soft tissues and liquefaction of organs. Under average temperature and climatic conditions, the earliest changes in putrefaction generally involve the anterior abdominal wall and tend to occur between 30 and 72 hours after a person’s death. After a period of about one week, putrefaction progresses to the point of gas formation. When the body’s soft tissues have shrunk and its putrefactive juices have gradually drained away, the body’s overall speed of decay is seen to reduce appreciably (Jain 2004). There is a considerable variation between the onset, and the rate that putrefaction progresses in a body. The general rule of this progress is that if the onset of putrefaction is rapid, is progress is accelerated and vice versa. Other factor that affect it include an individual’s life style with obese individuals putrefying faster than lean individuals. Estimating the Time of Death Using the Concurrence Method This method involves a number of key strategies that all seek to try and estimate the time of death by comparing the death with the occurrence of a number of events. An example of concurrence is examining the extent of the digestion after a victim’s last known meal or the stopping of a wrist watch due to the effect of a blow in the course of an assault (Snow 2005). The detection of soot in a cadaver’s airways in the event of a fire is useufl as it will indicate that the victim was alive when the fire started. However, in the event that a fire victim does not have soot in his airways, this can indicate that the victim died prior to the fire and as such, did not inhale smoke from the fire. Environmental and associated concurrence methods include uncollected newspaper and mail can also help to indicate a person’s time of death as this can be easily calculated from the last time that the person collected the mail and newspapers (Snow 2005). Lights being on or off can also help to indicate the time of death. If the lights are on, the victim probably died during the night but if the lights are off, it is quite probable that death occurred during the day. The presence of food on the stove or in the refrigerator help in indicating the time of death based on the victim’s meal times. Based on their date of expiry, food products in the refrigerator can also help in providing an estimation of the date within which the victim died. Other methods include the type of clothing that are found on the body. In addition to helping provide an estimation of the season within which a person died, clothing can also help in estimating the time of death as certain clothing such as pajamas are usually worn at specific times of the day (Snow 2005). The presence of receipts and sales slips in a person’s clothing can also help in indicating when the person was last spotted alive. Anamnestic evidences can include evidences such as a person’s engagements and appointments. If a person managed to make it to one appointment or engagement but failed to make it for another engagement, it is possible to estimate the time of death based on these two engagements. Answered and unanswered correspondences such as emails, text messages and phone calls can also be of help in providing an estimated time of death as similarly to appointments and social engagements, the time between which an individual answered and then failed to answer subsequent correspondences can help in providing an estimated time of death. Conclusion The determination of a person’s time of death based on the post mortem findings is perceived to be the most thoroughly investigated problem in forensic medicine. While there is no method that can singularly be used in providing a good estimate of the time of death, it is however quite possible to use a number of different corporal, environmental and anamnestic evidences to help in accurately estimating the time of death. The determination of the time of death has never been considered to be an exact science but with the help of science and a number of sound investigative techniques, it is possible to obtain close estimates.   Bibliography Jain B. 2004. Guide to Forensic Medicine & Toxicology. B. Jain Publishers. Pramod et al., 2014. The mystery surrounding the time of death”: post-mortem findings as an aid for forensic investigation. Anil Aggrawals Internet Journal of Forensic Medicine and Toxicology, 2014; Vol. 15, No. 1 (Jan - June 2014). Available from: http://www.anilaggrawal.com/ij/vol_015_no_001/papers/paper001/time_of_death.do Snow, R. 2005. Murder 101: homicide and its investigation. Westport, Conn. : Praeger Publishers. Read More