This will, of course, depend on the nature of the crime and the evidence the police can find about the timing.

You should analyse it in the following way:

a) Witness evidence

This is, of course, generally less reliable than scientific evidence. You must check on the basis for the witness's evidence.  Did the witness have any clock, watch or other means as a "yardstick"  by which to time the incident? Did something else occur, such as a train or bus going by, or a TV  programme beginning, which helped the timing? If any of these are yardsticks for the witness, then the actual time when the train  passed, or the programme actually began, must be separately checked.

TV programmes are possibly the most common way in which witnesses times events that they see out of their windows, or hear during the course of an evening.  TV companies hold very accurate logs of when programmes begin - and when the ad breaks are shown.

You must also look at the reverse side of this coin - if the witness to timing had access to any of the above yardsticks and they are not mentioned in evidence, why were they not mentioned? Never believe that just because something is not mentioned it is because the police were too dumb to think of asking about it.

Some timing witnesses give different times to others - this may require visits to these witnesses to ascertain which is the more reliable.

CCTV evidence can be very helpful in fixing the time of the crime. However, it is essentially in the same category as witness evidence, for it ultimately depends on human expertise - and is subject to  human error.

b) Scientific evidence.

Scientific evidence is usually of little use in fixing the time of a crime - unless the case is one of murder. In murder, the scientific evidence becomes pre-eminent.

In some cases the first question may well be where was the victim killed? The environment of that location can be vitally important to the next question - when was the victim killed?

This is no place for a full account of the means by which time of death is estimated. In any case, it is still not an exact science. And .you must study various books on the subject before reaching any definite conclusion.

For the location of the crime, you should first look to the pathologist's reports and in particular what the pathologist has to say about hypostasis.  This tells us if the body was moved  at some significant time after the murder - perhaps put into the boot of a car - and moved to the place where it was found. This is sometimes done to make identification  more difficult ( away from the home area of the victim) or simply to make discovery of the body more difficult.

Further proof of the location of the crime may lie in the reports of the scientists engaged on the case. Dirt on the shoes and clothes, fibres on the clothes etc may all point to a location different to the one where the body was discovered. A violent struggle in a countryside location will inevitably leave foliage and such on the victim. The absence of this may be significant.


The scientific methods  of determining time of death  are, basically, five:

a) Body temperature.

There are many variables in this - the time when the body temperature was taken - which part of the body it was taken from - the ambient temperature where the body was found, not only when the body temperature was taken, but throughout the period since death (work that one out!). In many cases the temperature will be taken at the scene - and also at the post mortem. Sometimes a rate of temperature loss can be detected and this may be "back-dated" to estimate a time of death. However, the ambient - or external location  - temperature is important. When the body is approaching the temperature of its surroundings, estimate by temperature is liable to serious error.

You should, as routine, get the weather record for the area for the relevant period. You can buy this from the Meteorological Office in Bracknell, Herts.  However, in the short term, local weather forecasts in the local newspapers may suffice as a test of whether the weather is of relevance.

Your job at this time is not to take on the pathologist about the time of death that as written in the pathology report - but to check that all the routine checks were done and reported on.

b) Stomach contents.

In all cases of murder, attention should be directed to the stomach contents. The stomach contents will give indication of the extent of digestion which has taken place and, therefore the interval of time since the ingestion of the last meal prior to death. An ordinary meal leaves the stomach in about four hours

This in turn depends on witness evidence about when the victim last ate a meal - and what that meal was. All the usual provisos about witness evidence apply  here. However, in many murder cases, searching for the victim has often begun as a "missing person" inquiry - and one of the routine questions on the missing persons form is - when did the missing person last eat? This is so that the officers searching can go potential places where the missing person might have been seen eating. People generally eat every four to five hours during the day. The witness giving the information on a missing person is usually desperately trying to help the police - and  not traumatised yet by the murder of a friend or relative.

Having read this, do not come to any quick conclusions that may be contrary to the pathology report - there are many variables and you would need to make much greater study before forming a definite opinion. at this stage ware simply checking that the correct things have been done.

Stomach contents are also important for the toxicologists. They look for poisonous substances or, generally, drugs - either prescription or non-prescription. They can determine the cause of death and, in some cases, probable time of death. So you should check if there is a toxicology report - and if you feel there should have been one, put it on the list of "undisclosed documents".

c) Rigor mortis.

Rigor is the stiffening of the body after death.  It depends very much on the atmosphere around the body - temperature, humidity etc. As a rule, stiffening will be established after ten to twelve hours. In the majority of cases, rigor will have commenced to pass off in about 36 hours.  Some pathologists consider this to be too general a rule. Rigor is usually apparent at 4 hours, but in some cases it has been observed to be complete after only 6 hours. It appears first in the eyelids, then the face, the lower jaw and the neck. Even the 36 hour rule is far from exact - some corpses have still been  in rigor 40 to 60 hours after death.

Rigor is affected by many conditions  and might easily be dismissed as a guide towards the time of death.  Strong muscularity in a corpse can lengthen the duration of rigor. In cases involving young women, rigor might be often of shortened duration . However in such cases another factor can be important. Rigor can be accelerated by gross violence or exertion just before death.

What is important here is whether the pathologist makes the best observation he or she  can in the circumstances. There should be a note of rigor at the scene, at the post mortem -and at the end of 36 hours from the projected time of death as estimated by other methods.

There is also the very unusual condition of "instant rigor" or "cadaveric spasm"- where stiffening occurs immediately on death. This is mostly found in suicides.

d) Hypostasis ( also known as post-mortem lividity or lividity staining)

Hypostasis is due to the engorgement of the capillaries by gravitation of the blood. When a dead body lies on the ground, blood inside it drops to the lowest points and fills the cells in that area of the corpse.

It occurs in all  parts of the body, but will be absent where there are restrictions on the body - such as from collars, waistbands and other such items of clothing.  It also does not occur at the part of the body in immediate contact with the ground. Hypostasis also affects the internal organs.

So, if a murdered person falls onto the back and lies there for an hour or so, and then is moved or turned over, the hypostasis will have begin to show on the back, and then other hypostasis appears in the new areas of contact. This is common in cases where bodies are moved by putting them into a car boot. Initial hypostasis may be in the back, but secondary hypostasis can then appear  on the side of the body. 

Hypostasis generally begins to form within an hour and will generally become partially "fixed" within 4 hours and wholly "fixed" after about 12 hours.

Beware however - hypostasis is not an area for the amateur to be making deductions in. It can easily be confused by the inexpert eye with bruising. Only an incision in the body can determine which is which.  Our job here is not  to make any accusations - but merely to note whether notes on hypostasis might have be useful in the case we are looking at - and whether the pathologists took note - and photos - of it. 


e)  Putrefaction:

This can only apply where a body is discovered long after death - and the estimate of time of death can never be to the hour - or even the day. There are many aspects of this, the decay of body tissue, the invasion of the body by insects etc. It depends on whether the body has lain in earth, in the air, or water, whether it has been cold or hot, or in very moist circumstances. Maggots, or larvae cases on the body prompt pathologists to investigate the life-cycle of the type of maggot involved. Being so inexact, this method of estimating time of death can only help  an innocently convicted person if he or she has been out of the country  for a long period - during which the murder took place.


There are other means of estimating time of death, the means largely depending on the circumstances of the crime. 

If, after your brief excursion into the estimation of time of death, there appears to be a poor base for the estimation, it may well be worth at this stage reading what the judge at the trial said about this. Did he accurately quote the pathologist about the time of death - and did the quotation reflect the truth of the report?

This is an area that you should bear in mind throughout your consideration of the police investigation and the trial - some judges, indeed some barristers - are not strong on pathology and forensic science, particularly the latest techniques. They may misunderstand and mis-quote the scientific evidence -  and give the jury a wrong impression. Yet the scientists and pathologists would never dare protest. Some defence barristers, prompted by the scientist in the seats behind them, sometimes raise objections - or "clarification" - during the judge's summing-up. But it is a brave barrister who does so.