The second point is that there was no trace of oil or grease stains on his clothing. You may object that he never went near the machinery in the suit he was wearing when you found him. But still I maintain that oil particularly has a way of penetrating to the underclothing, and in this case the vest and drawers bore no signs of it.’
‘How in the world do you know all this, sir?’ exclaimed Harold in amazement. ‘Nothing nearly so detailed came out at the inquest!’
Professor Priestley smiled indulgently. ‘It seems that I have to some extent betrayed myself,’ he replied. ‘I had not meant to inform you of the fact at this stage, but Inspector Hanslet is a friend of mine. He is a man of very wide interests, as befits an officer charged with such important duties, and two or three years ago he happened to read a paper of mine on Methods of Psychological Deduction, in which, I venture to say, I succeeded in refuting some very widely-accepted theories. But no matter. Since that time he has often called upon me to ask my assistance in the correlation of scattered facts. I approached him three or four days ago, and he very willingly went over the case with me. He was very much interested in it then, although I expect that the verdict of the coroner’s jury has now allayed his anxiety. I did not, of course, tell him that I was in any way interested in you.’
Harold gave a gasp of astonishment. The idea of this militant mathematician taking an interest in criminal cases was so novel that it seemed absurd. Mathematics was to him merely a jumble of queer signs and Greek letters; he had never considered it as a science applicable to human events.
‘However,’ continued the Professor, after a pause, ‘that is by the way. The point I wish to make is that up to the present we have discovered nothing of great assistance towards establishing the identity of the deceased. We will now turn to a matter of even greater interest, and that is the cause of the man’s death.
‘You will remember that by your own statement the first thing that struck you was that the man’s clothes were soaking with water. Investigation showed that the bed where he was lying was also very wet. The bed was in such a position that rain cannot have blown upon it from the window, and there was no sign of a leakage in the roof. Either, then, the man’s clothes were soaked when they entered the room, or they were deliberately wetted after arrival. The fact that the carpet of the room showed signs of moisture is compatible with either theory. We must remember that, although there appears to be evidence of the source of the water, this evidence is not necessarily conclusive.’
‘But surely,’ interrupted Harold, ‘the tracks leading up from the canal—’
The Professor held up a protesting hand. ‘Let us wait until we come to that point,’ he said. ‘We are not at present considering how the body gained access to your rooms. Having established the condition of the corpse when found, that is, soaked with moisture and lying on its back on your bed, we come to the cause of death.
‘Now, as a result of expert medical evidence, the coroner’s jury returned a verdict of death from natural causes. A post-mortem had been held, and we must assume that the body had been very carefully examined, internally and externally, by experts familiar with the various methods by which life is terminated. It seems that these experts were able to rule out violence or poison as the cause of death. Now, I am no doctor, so I am compelled to rely upon the statements of others in this case. Until any fact appears to controvert this conclusion, we may accept it as probable.
‘Examination of the body, however, revealed two salient facts. The first was that the left forearm bore minute marks—the number I have not been able to ascertain—such as might have been caused by a hypodermic syringe. From the position on the arm these marks might have been self-inflicted. The experts stated that the fact that no analytical or pathological traces of drugs could be discovered made it impossible that death could have been caused by some toxic injection. The second fact was that the deceased suffered from an affection of the heart of long standing, and of a nature which frequently terminates fatally. The existence of this heart affection caused one of the experts to put forward the suggestion that the marks on the forearm were the result of self-injection of some drug prescribed to relieve the heart, and that these injections had been made sufficiently long before death for all traces of the drug used to have vanished. I think that is a fair summary of the medical evidence?’
Harold nodded. He had learnt by now that interruptions of the Professor’s train of thought were not welcome.
‘Very well, then,’ continued the Professor, ‘you will agree, I think, that this evidence is mostly negative. Pressed to account for the fact that the man was dead and not alive when found, the medical witnesses—I say witnesses, for the police surgeon had sought the assistance of a Home Office expert—suggested that the deceased died of heart failure, brought on by sudden immersion on a cold night affecting an already-weakened organ. That the man died of heart failure was patent; I suppose most people die because the heart ceases to function for some cause or other. Whether this man’s heart failed for the causes alleged, I cannot say. There may have been facts supporting the experts’ view which are hidden from the mere lay mind. Were I to give an opinion, I should say it was a mere guess, although an extremely plausible one. In any case, the coroner and his jury seized upon it, and their verdict was the result.
‘The next point of enquiry is obviously the time when the man died. The police surgeon, who saw the corpse at about five o’clock in the morning, expressed an opinion that the man had been dead not less than about nine or ten hours. Again, I have no knowledge or experience in such a matter, and we may provisionally accept this estimate as correct. In which case, the man may be assumed as having been dead by eight or nine o’clock the previous evening. According to your evidence you left your rooms at about four o’clock that evening, at which time, to your knowledge, the rooms contained no man, alive or dead.’
‘That is so, sir,’ replied Harold, seeing that the Professor paused, as though for confirmation. ‘I fancy that the police had a vague suspicion that the body had been there all the time, since the doctors could only say that the man had been dead not less than eight or nine hours and not more than about twenty-four.’
‘Possibly, possibly,’ agreed the Professor. ‘But certain other evidence, which, I confess, interests me far more than the question of the identity of the deceased, seemed to point in quite another direction. I mean the evidence concerning the means by which the corpse obtained access to your rooms. As you know, I have never visited Number 16, Riverside Gardens myself, but I received a description, an inadequate one, I admit, from a friend who has been there.’
‘Inspector Hanslet again, sir?’ suggested Harold.
‘No,’ replied the Professor. ‘His mind was already made up. I wanted the description from someone who was unaware of the details which had been discovered. Evan Denbigh was able to supply me with the outline of what I required.’
‘Denbigh!’ exclaimed Harold, with some embarrassment. ‘Oh yes, of course, he was there once, about six months ago. He came—’
Professor Priestley waited for the end of the sentence, but Harold had relapsed into silence.
‘He told me why he went,’ he said quietly. ‘He was one of your friends who thought that you were making a fool of yourself. I fancy he went to see if you could not see reason.’
‘Well, as a matter of fact, that’s what he did come for,’ agreed Harold. ‘Jolly decent he was about it, too, really. He can’t have seen much of the place, though. I was dressing for dinner, I had half my clothes flung about the sitting-room, and after he’d been there about ten minutes I went into the bedroom to wash and left him spouting to me through the door. He never saw the bedroom, where I found the body, at all.’
‘So he told me,’ replied the Professor.
