Review ArticleEstimation of the time of death based on the assessment of post mortem processes with emphasis on body cooling
Introduction
Precise estimation of the TOD is a difficulty accompanying forensic medicine from its very beginning. It is one of the fundamental tasks of the forensic pathologist summoned to the scene where a body was found. Following a preliminary diagnosis of the cause of death, the pathologist decides on the course of investigative actions. In situations with suspected crime the pathologist supports the prosecutor’s office and the police by leading investigations to the appropriate direction.
From the point of view of criminal law, a precise estimation of the TOD enables to verify witnesses’ statements, limit the number of suspects and assess their alibis, especially since nowadays it takes less time to travel even long distances. Not precise or incorrect estimation of the TOD may cause wrong statements by a suspect, e.g. of being far away from the locus at the time of the crime difficult to disprove.
Determination of the TOD sometimes also gains relevance regarding civil law, since it may have impact on the order of inheritance or possible commitments resulting from the order of deaths. Such problems may occur if corpses of two or more related persons are found simultaneously (e.g. in case of multiple homicide or accident with several deceased).
Despite attempts over a hundred years to develop methods for precise estimation of the TOD, the accuracy of these methods, both when using one of them or combining several of them, still leaves a margin for improvement. During the first 6 h after death, there is at least a 2 h margin of error, but in the next 14 h, the margin of error increases to at least 3 h, and during the following 10 h this margin of error increases to approximately 4.5 h. The precision of the conventional methods decreases significantly with time. Therefore, usually since about 24 h post mortem all estimations are rather rough approximations [1], [2], [3]. Nonetheless, there is a potential to decrease the time of death estimation error, in particular regarding the very early post mortem period, by choosing eye as the temperature measurement site.
Currently known methods of TOD estimation can be divided into two groups:
- 1.
The first group comprises methods based on analysis of the process of cooling of corpses and the body temperature is measured (temperature-based methods). Methods based on the body cooling process are deemed to be more precise when used in the early post mortem period (first 24 h).
- 2.
The second group consists of methods based on assessment of post mortem processes occurring in corpses. Some of them, dealing with the early changes, can be applied when the time since death is counted in hours and others, based on late changes, even if the post mortem interval is counted in months or years.
Section snippets
Methods based on the body cooling process
One of the first authors to publish important work on the estimation of TOD based on post mortem decrease in body temperature was Harry Rainy, Professor at the University of Glasgow [4]. Reviewing the literature, one can find also articles dating earlier. Davey’s work is cited [1], describing measurement of temperature in eight corpses of British soldiers who had died in Malta in 1828, and then another 10 who had died in a colder climate (i.e. Great Britain). However, Davey did not manage to
Methods based on assessment of other post mortem changes
Among methods for estimation of the TOD being based on post mortem changes in the body during the first few days following death, the following appear to be noteworthy: assessment of intensity and movability of hypostasis (lividity), development and receding of rigor mortis, and drying out of the cornea. Examination of supra-vital reactions may be also important, namely assessment of response of skeletal muscles to mechanical stimulus (Zsako’s phenomenon) or electrical stimulus, the reaction of
Methods combining body temperature measurements and observation of post mortem changes
A number of authors recommend that determination of the TOD should be based on combined application of different methods in order to increase the overall accuracy. Body temperatures may be taken from more than one site (e.g. rectum, brain [81] and liver [48], [49]), and body temperature assessment can be complemented by other methods of TOD estimation [25], [82] or several different non-temperature related methods can be used as well [83], [84]. According to Henssge and Madea [25], particularly
Conclusions
As pointed out, there have been invented numerous temperature-based methods during the last 100 years in order to estimate the TOD, but none of them alone allows to define the post mortem interval with absolute precision. Therefore, during the early post mortem period (up to 24 h) one simple method as above mentioned “rule of thumb” or the more detailed Henssge nomogram is used in practice, complemented by assessment of hypostasis and rigor mortis, sometimes also together with regard to some of
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