Estimating the time of death – science or art?

A reliable estimate on the time of death can only be made during the first one to two days after death and even during that period there is a pretty wide margin of variance. After this period we are all well advised to not make exact claims on when death occurred.

One of the more accurate ways to estimate the time of death during the first 24 hours post mortem is based on body temperature. After death the body temperature will slowly decline towards the ambient (surrounding) temperature. An excellent tool for estimating the time of death prior to the body reaching the surrounding temperature is the easy to use Henssge Nomogram. Based on the rectal temperature of the deceased, the ambient temperature and application of corrective factors (size of the body, clothing and coverings, movement and humidity of air, immersion in water) the time of death can be estimated with a permissible variation of 95% in most instances assuming normal body temperature and surrounding temperatures ranging from 14 to 95 degrees Fahrenheit.

 The other tools used during the early post-mortem period are establishing the levels of rigor mortis (RM – generalised muscular stiffening) and livor mortis (LM – dark purple discolouration of the skin resulting from the gravitational pooling of blood in the veins and capillary beds after circulation has stopped).  Changes related to the body based on these physiological processes are far from accurate, but they do give us some additional indications concerning the time of death during the first couple of days.

The important facts to remember (when dealing with air exposed bodies) is that rigor mortis is complete after about 8 hours and disappears in 24-72 hours – providing at least a time window during which RM is present, which can be combined with the fact that LM discolouration can not be blanched (whitening of the skin when pressed) after about 8 hours.

Beyond the 48 hr point in time estimation of the time of death becomes an artful science with a wide range of error

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