At the committal proceedings, the pathologist called by the
prosecution, Dr. J.E.Ennis, had given as his professional opinion that Angus Sibbett had died some time between 12 midnight and 4:00am on 5th January.
This opinion was based on the temperature of the body at the time of examination (1:15pm), this being the only test conducted which had a bearing on the time of death.
At the time of examination the body temperature was 64 degrees fahrenheit.

In a statement prepared for the defence by Professor Francis Camps for use at a possible appeal against the findings of the Assize Court (permission to appeal was not in fact granted) it was testified that the temperature of a human body is normally assumed to lie within the range of 98.4 and 99.4 degrees fahrenheit at time of death; the temperature loss between the time of death and the time of
examination was thus 34.4 to 35.4 degrees fahrenheit.
Furthermore, Professor Camps testified that according to data
assembled by forensic pathologists, and on the basis of his own
experience, the rate of temperature loss expected after death lies between 2.6 and 3.2 degrees fahrenheit per hour.
On this basis, taking the maximum temperature loss and minimum temperature of death, and vice versa, the extreme limits between which the victim had been dead at the time of the examination of his body would be 10.75 and 13.61 hours.
This would mean that he died between 11:39pm and 2:30am.
Therefore, in his original evidence, Dr. Ennis’ estimate of the time of death was consistent with established procedures.

However, Dr. Ennis changed his opinion fairly significantly when
giving evidence at the trial.
While retaining the “wide range” of midnight to 4:00am for time of death, he went on to express the opinion that it was “much more likely that death occurred in the earlier part of that period.”
In other words, it was most probable that death occurred between 12 midnight and 1:00am.
Had that opinion been allowed to stand, the accused could not have been found guilty since it would have disproved the prosecution
theory.

In cross-examination, Dr. Ennis was naturally asked to explain the basis on which he was inclined  to the opinion that death had
occurred around midnight when his original range lay between
midnight and 4:00am. He justified it in relation to two facts of which he stated he had been unaware of at the time of giving his original
evidence:

a) that the car heater had been switched on (i.e. the heater fan had been working) when the body was found;
and
b) that rigor mortis had been ‘confirmed’ at 6:00am when the body had first been examined by Dr. Hunter.

It is worth looking at both these considerations carefully.
As far as the first is concerned, the implication appears to be that Dr. Ennis was assuming that the heater had been blowing hot air into the car for at least a substantial part of the time after death. In
evidence he stated that “For the latter half of the period I am quite sure that the cold air was being blown on to the body.” This implies that for the first half (i.e. between shortly before midnight and 5:15 am, when the body was discovered – some 5 1/2 hours) the heater was blowing relatively warm air. This is quite inconceivable and, indeed, in direct conflict with the evidence. The radiator of the Mark X Jaguar had been fractured, so that the water drained away, and a motor engineer testified that the engine had stalled – it had in fact been on the verge of seizure – at the time it stopped; warm air could not have been coming through the heater for (at the very longest) half an hour. For roughly five hours, therefore, the heater fan had been blowing cold air (the temperature was below freezing) rather than warm air over the body. This ‘additional knowledge’, in other words, pointed to a raising rather than a lowering of the estimated rate of temperature loss.

The second factor – the observation of rigor mortis – is more
complex. Dr. Hunter, the doctor who first examined the body at the crime scene, made no mention of this fact before and at the
committal proceedings.
Furthermore, since the pathologist, Dr. Ennis, declared himself also unaware of the fact at the time of proceedings, it must be assumed that no mention of this obviously important observation had been made by Dr. Hunter in the written report he had submitted to the authorities at the time.

There was one other strange incident that happened during the trial in this context.
The first witness called by the prosecution to testify to the discovery of the body was Mr. Marshall, the first-aid trained colliery worker, who felt for a pulse at the crime scene when the body was first discovered, but he was not in fact the first person on the scene.
The first one to arrive was Mr. Tom Leak, a worker at the same
colliery, who attended the trial out of a sense of curiousity but was somewhat upset that he was not called upon by the prosecution to give evidence.
The defence decided to invite him to give evidence on their behalf and Mr. Leak agreed to do so. A few hours later, he telephoned the defence solicitor to say that the police contacted him and asked him to be a witness for the prosecution and he agreed.
Apparently the police were exceedingly anxious for him to give
evidence for the prosecution, so on the following day he appeared as a prosecution witness. The defence found it strange that such an odd procedure had been adopted for what was apparently a routine, ‘neutral’ witness.
When Mr. Leak did give his evidence (some 17 witnesses appearing in between his colleague Mr. Marshall and himself) a possible reason for this curious information emerged.
In his examination by the prosecution, Mr. Leak was asked largely routine questions about the circumstances in which he found the body, although oddly enough, counsel for the prosecution suggested that Mr. Leak found the experience of finding a dead body a ‘rather an alarming experience’, a suggestion which counsel thought
unnecessary to ask his colleague Mr. Marshall, who had the same
experience.
It seems that the prosecution was trying to suggest to the jury that Mr. Leak might have been so upset by the shock of seeing a dead body that he may have confused some of his facts – in other words, they were trying to discredit the witness.
Mr. Leak, being an experienced and seasoned collier merely gave the laconic answer: “Well, I have witnessed death before, Sir.”
The prosecution did not pursue the matter any further.
In cross-examination, however, Mr. Leak revealed one interesting fact. Shown an official photograph of the body on the rear seat of the car, Mr. Leak categorically denied that the legs had been bent in the way shown in the photograph when he discovered it; the leg he had felt had been straight along the seat. He had not bent it.
When the direct suggestion was put that someone must have bent the leg after he had left the car and before the photograph was
taken, Mr. Leak replied “It appears to be that way.”
He was not cross-examined on this point. Nor did Mr. Justice
O’Connor make any reference to it in his summing up.
Yet the inference is clear: if the body was moved after Mr. Leak had left it, rigor mortis could scarcely have been established.
If it had, the movement would have broken it.
Could this have explained why no reference to it had been made by either Dr. Hunter, the G.P. who arrived half an hour later, or Dr.
Ennis, the pathologist, at the committal proceedings?

This is a case based on circumstantial evidence in which, as
remarked earlier, the balance of probabilities is of the essence.
In normal pathological practice a range of temperature loss of 2.6 to 3.2 degrees fahrenheit an hour is adopted; many factors can
influence the position within this range thought applicable to a given case, but the ambient temperature is obviously a dominant
consideration.
Here is a case of a body lying in freezing temperatures for some 13 hours.
Can the balance of probability be said to lie in favour of a
temperature loss rate at (or even below) the minimum extreme?
In Professor Camps original statement for the defence he asserts “There is no justification for choosing, as between these terminal
figures, the lower figure in preference to any other.”
He points out that the mean figure within the range would have placed the time of death at 1:30 am. If this time were accepted as a probable time of death, the two accused could not possibly have been guilty of the crime as it was asserted by the prosecution, to have been committed.