There was a delay while papers were being handed around the court. Angus Smythe was given a set as he squatted on his chair, and there was a long silence as everyone scanned the flimsy carbons. After about ten minutes, with the court beginning to get restive, Prideaux began speaking again.
‘Dr Pryor, could you just summarize, in a way comprehensible to us laymen, the import of this work? First, can you tell me why this research was done in various parts of the world? Surely there has not been a global epidemic of potassium homicides?’
Richard risked a grin, in spite of the fraught circumstances.
‘Not at all, sir! This was done for a totally different purpose. Estimating the time since death is a very important forensic problem, because of alibis and the like. Most methods are notoriously inaccurate, but these gentlemen discovered the fact that potassium in the eyeball fluid rises progressively after death. They have been trying to use this as a measure of time since death by making a graph of potassium level against the number of hours – or indeed days – that have elapsed since death.’
‘So what is the relevance to this case, doctor?’
‘The second post-mortem on Mrs Parker was not carried out by Dr Smythe until the third day after death. Though the results of the three researchers are not identical, it is patently obvious that the concentration of potassium found by Dr Smythe is well within the expected levels for that period of time, some seventy-eight hours. So the interpretation that this level must have been due to the injection of extraneous potassium is now quite unacceptable.’
Nathan Prideaux wanted to nail this idea down firmly in the minds of the jury, who by now were looking bemused at this sudden turn of events.
‘Dr Smythe claimed that the eye fluid is immune from the changes after death that make the blood levels of potassium useless. What do you say to that?’
‘I’m afraid it’s just not true. This was assumed, but until now no one has actually investigated it. Admittedly, it is much slower than in the rest of the body, but this new research shows that potassium leaks out of the cells in the retina – the inner lining of the eye that allows vision – and this is why they hope it will provide a new method of determining the time of death.’
Richard Pryor, at Nathan’s request, went on to quote facts and figures from the research papers to consolidate what he was claiming, while the judge, barristers and prosecution expert followed it on the documents they had been given. From the glazed look on the faces of some of the jury, it was obvious that they had no idea of what he was talking about, but soon Prideaux put them out of their misery by diverting on to a new tack.
‘Dr Pryor, I think you also have a second reason for disputing Dr Smythe’s conclusions?’
‘Indeed, though I admit that I, too, was unaware of it until I began researching all aspects of potassium and eye fluid. Unlike the new discoveries in Germany and America, apparently this has been known to physiologists and biochemists for a long time. I’m afraid it’s a problem with all sciences, that there is so much knowledge available, but it tends to be kept in separate boxes, until someone actively seeks it out.’
‘And what was in this particular box, doctor?’
‘Dr Smythe quite correctly said that death occurs very rapidly on injection of strong potassium chloride solution – which is the allegation in this case. The heart stops very quickly, perhaps not instantly, but within a few moments. That is why it is used by vets to dispatch animals.’
‘And what is the significance of that?’ asked the QC.
‘When substances such as potassium are injected into the bloodstream, it takes up to three hours for the substance to reach its maximum concentration in the eye fluid. This “equilibration” as it is called, cannot proceed if the heart has stopped, as there is no circulation to drive the substance around the body to reach the eyeball. So if an injection of potassium is sufficient to cause rapid death, there is no way that this extraneous amount can get into the eye fluid! Any rise in potassium must therefore be due to post-mortem leakage from the cells in the retina.’
He lifted up another document from his collection. ‘Though I said this has been known for years, I sought advice from clinical biochemist Professor Lucius Zigmond of St George’s Hospital in London, who is an expert in what are called “electrolytes” such as potassium. He has provided a statement in which this delay in equilibration is positively confirmed, and which is also contained in a number of standard textbooks.’
This statement was again handed around the court as a sheaf of carbon copies, the sworn original going to the judge for his inspection.
Nathan Prideaux took over again and asked the judge to accept all these papers as sworn evidence, entering them with exhibit numbers into the trial record.
There now seemed to be a hiatus in which the whole court was holding its breath, waiting to see what was to happen next in this drama.
Mr Justice Templeman finished reading the last of these documents, then looked down at both the leading counsel. ‘Where does this leave us now, gentlemen?’ he asked evenly. ‘Do you want to cross-examine Dr Pryor first, Mr Gordon? Or do you wish to have Dr Smythe back in the witness box, Mr Prideaux?’
The prosecuting counsel shook his head almost helplessly as he declined the invitation. He would dearly like to have had the chance to discuss this turn of events with his expert, but once any witness began giving evidence no communication was allowed between him and counsel.
‘If it pleases your lordship,’ replied Nathan, in the traditionally obsequious language of the courts, ‘I would like to hear Dr Smythe’s reaction to these propositions.’
There was a general shuffling about, as Richard came down to sit on Angus’s chair, while the Scot hauled himself back up into the witness box. As they did so, the two prosecuting barristers engaged in an animated, muttered discussion, while their defence counterparts sat back impassively until the judge invited Prideaux to begin his cross-examination.
‘Dr Smythe, you have heard what Dr Pryor had to say and you have seen the various sworn statements of the other forensic experts. Is there anything in them which you do not accept or wish to dispute?’
Richard, sitting below the high witness box, fully expected the fiery Angus to begin a staunch counter-attack and was amazed when the man from Oxford immediately capitulated, contradicting his reputation for doggedly fighting off any opposition to his opinions.
‘I have no option but to agree with all Dr Pryor’s propositions,’ said Angus. ‘These are reports from reputable scientists – in fact I know of Dr Stoddart from other work. The publications have been accepted by well-known international medical journals. I did not know of this new work – and I very much doubt if the majority of my colleagues know of it. The delay in equilibration seems to be a long-accepted fact, but again I confess that it had never come to my knowledge, as I had never had occasion to seek it out.’
He nodded an acknowledgement down to Richard Pryor.
‘I can only compliment Dr Pryor on such a diligent search of recent research and literature, and I unreservedly accept the conclusions which he has put forward. I withdraw my previous interpretation, which I now admit to being erroneous.’
Amid another buzz of excitement in the court, Nathan Prideaux turned to the judge.
‘My lord, at this juncture I would like to make a submission to you.’
Doris hissed in Moira’s ear. ‘He’s going to ask the judge to consider directing the jury to return a verdict of not guilty.’
But for once, Doris was wrong, as Mr Justice Templeman held up a hand towards the defence counsel.
‘I think, Mr Prideaux, that will not be necessary. I am sure that Mr Gordon will not contest the fact that his witness has withdrawn virtually all his expert opinion which goes to the heart of this case. In my view, there is nothing left that can go to the jury for their decision. I therefore intend discharging the jury and also discharging the defendant forthwith.’