Dr. Thorndyke Omnibus Vol 5

by R. Austin Freeman

  "Ha!" I exclaimed. "Then you did find something significant, in spite of your pessimistic tone at the time? I may say, Thorndyke, that I had a feeling that you went to that house with the definite expectation of finding some specific thing. Was I wrong?"

  "No. You were quite right. I went there with the expectation of finding one thing and a faint hope of finding another; and both the expectation and the hope were justified by the event. My main purpose in that expedition was to obtain samples of the wallpaper from Monkhouse's room, but I thought it just possible that the soot from the bedroom chimneys might yield some information. And it did.

  "To begin with the wallpaper: the condition of the room made it easy to secure specimens. I tore off about a dozen pieces and wrote a number on each, to correspond with numbers that I marked on a rough sketch-plan of the room which I drew first. My expectation was that if—as I believed—arsenical candles had been burnt in that room, arsenic would have been deposited on all the walls, but in varying amounts, proportionate to the distance of the wall from the candle. The loose piece of paper on the wall by the bed was, of course, the real touchstone of the case, for if there were no arsenic in it, the theory of the arsenical candle would hardly be tenable. I therefore took the extra precaution of writing a full description of its position on the back of the piece and deposited it for greater safety in my letter-case.

  "As soon as I reached home that day I spread out the torn fragment on the wide stage of a culture microscope and examined its outer surface with a strong top light. And the very first glance settled the question. The whole surface was spangled over with minute crystals, many of them hardly a ten-thousandth of an inch in diameter, sparkling in the strong light like diamonds and perfectly unmistakable; the characteristic octahedral crystals of arsenious acid.

  "But distinctive as they were, I took nothing for granted. Snipping off a good-sized piece of the paper, I submitted it to the Marsh-Berzelius test and got a very pronounced 'arsenical mirror,' which put the matter beyond any possible doubt or question. I may add that I tested all the other pieces and got an arsenic reaction from them all, varying, roughly, according to their distance from the table on which the candle stood.

  "Thus the existence of the arsenical candle was no longer a matter of hypothesis or even of mere probability; it was virtually a demonstrated fact. The next question was, who put the arsenic into the candle? All the evidence, such as it was, pointed to Barbara. But there was not enough of it. No single fact connected her quite definitely with the candles, and it had to be admitted that they had passed through other hands than hers and that the candle-box was accessible to several people, especially during her absence. Clear evidence, then, was required to associate her—or someone else—with those poisoned candles, and I had just a faint hope that such evidence might be forthcoming. This was how I reasoned:

  "Here was a case of poisoning in which the poison was self-administered and the actual poisoner was absent. Consequently it was impossible to give a calculated dose on a given occasion, nor was it possible to estimate in advance the amount that would be necessary to produce the desired result. Since the poison was to be left within reach of the victim, to be taken from time to time, it would be necessary to leave a quantity considerably in excess of the amount actually required to produce death on any one occasion. It is probable that all the candles in the box were poisoned. In any case, most of them must have been; and as the box was filled to last for the whole intended time of Barbara's absence, there would be a remainder of poisoned candles in the box when Monkhouse died. But the incident of the 'faked' medicine showed that the poisoner was fully alive to the possibility of an examination of the room. It was not likely that so cautious a criminal would leave such damning evidence as the arsenical candles in full view. For if, by chance, one of them had been lighted and the bearer had developed symptoms of poisoning, the murder would almost certainly have been out. In any case, we could assume that the poisoner would remove them and destroy them after putting ordinary candles in their place.

  "But a candle is not a very easy thing to destroy. You can't throw it down a sink, or smash it up and cast it into the rubbish-bin. It must be burnt; and owing to its inflammability, it must be burnt carefully and rather slowly; and if it contains a big charge of arsenic, the operator must take considerable precautions. And finally, these particular candles had to be burnt secretly.

  "Having regard to these considerations, I decided that the only safe and practicable way to get rid of them was to burn them in a fireplace with the window wide open. This would have to be done at night when all the household was asleep, so as to be safe from interruption and discovery; and a screen would have to be put before the fireplace to prevent the glare from being visible through the open window. If there were a fire in the grate, so much the better. The candles could be cut up into small pieces and thrown into the fire one at a time.

  "Of course the whole matter was speculative. There might have been no surplus candles, or if there were, they might have been taken out of the house and disposed of in some other way. But one could only act on the obvious probabilities and examine the chimneys, remembering that whereas a negative result would prove nothing for or against any particular person, a positive result would furnish very weighty evidence. Accordingly I collected samples of soot from the various bedroom chimneys and from that of Barbara's boudoir, labelling each of them with the aid of the cards which you had left in the respective rooms.

  "The results were, I think, quite conclusive. When I submitted the samples to analysis I found them all practically free from arsenic—disregarding the minute traces that one expects to find in ordinary soot—with one exception. The soot from Barbara's bedroom chimney yielded, not mere traces, but an easily measurable quantity—much too large to have been attributable to the coal burnt in the grate.

  "Thus, you see, so far as the murder of Monkhouse was concerned, there was a fairly conclusive case against Barbara. It left not a shadow of doubt in my mind that she was the guilty person. But you will also see that it was not a satisfactory case to take into court. The whole of the evidence was scientific and might have appeared rather unconvincing to the ordinary juryman, though it would have been convincing enough to the judge. I debated with myself whether I should communicate my discoveries to the police and leave them to decide for or against a prosecution, or whether I should keep silence and seek for further evidence. And finally I decided, for the present, to keep my own counsel. You will understand why."

  "Yes," said I. "You suspected that Stella, too, had been poisoned."

  "Exactly. I had very little doubt of it. And you notice that in this case there was available evidence of a kind that would be quite convincing to a jury—evidence obtainable from an examination of the victims body. But here again I was disposed to adopt a waiting policy for three reasons.

  "First, I should have liked to avoid the exhumation if possible. Second, if the exhumation were unavoidable, I was unwilling to apply for it until I was certain that arsenic would be found in the body; and third, although the proof that Stella held been poisoned would have strengthened the case enormously against Barbara, it would yet have added nothing to the evidence that a poisoned candle had been used.

  "But the proof of the poisoned candle was the kernel of the case against Barbara If I could prove that Stella had been poisoned by means of a candle, that would render the evidence absolutely irresistible This I was not at present able to do. But I had some slight hopes that the deficiency might be made up, that some new facts might come into view if I waited And, as there was nothing that called for immediate action, I decided to wait, and in due course, the deficiency was made up and the new facts did come into view."

  As he paused, I picked up Stella's medallion and looked at it with a new and sombre interest Holding it up before him, I said: "I am assuming, Thorndyke, that the new facts were in some way connected with this. Am I right?"

  "Yes," he replied, "you are entirely righ
t. The connection between that charming little work and the evidence that sent that monster of wickedness to her death is one of the strangest and most impressive circumstances that has become known to me in the whole of my experience. It is no exaggeration to say that when you and Stella were working on that medallion, you were forging the last link in the chain of evidence that could have dragged the murderess to the gallows."

  He paused, and, having replenished my glass, took the medallion in his hand and looked at it thoughtfully Then he knocked out and refilled his pipe and I waited expectancy for the completion of this singular story.

  18. THE FINAL PROOF

  "We now," Thorndyke resumed, "enter the final stage of the inquiry. Hitherto we have dealt with purely scientific evidence which would have had to be communicated to the jury and which they would have had to take on trust with no convincing help from their own eyes. We had evidence, conclusive to ourselves, that Monkhouse had been murdered by means of a poisoned candle. But we could not produce the candle or any part of it. We had nothing visible or tangible to show to the jury to give them the feeling of confidence and firm conviction which they rightly demand when they have to decide an issue involving the life or death of the accused. It was this something that could be seen and handled that I sought, and sought in vain until that momentous evening when I called at your chambers to return your diary.

  "I remember that as I entered the room and cast my eyes over the things that were spread out on the table, I received quite a shock. For the first glance showed me that, amongst those things were two objects that exactly fulfilled the conditions of the final test. There was the wax mould—a part, and the greater part, of one of the suspected candles; and there was the tress of hair—a portion of the body of the person suspected to have been poisoned. With these two objects it was possible to determine with absolute certainty whether that person had or had not been poisoned with arsenic, and if she had, whether the candle had or had not been the medium by which the poison was administered."

  "But," I said, "you knew from the diary of the existence of the wax mould."

  "I knew that it had existed. But I naturally supposed that the cast had been taken and the mould destroyed years ago, though I had intended to ask you about it. However, here it was, miraculously preserved, against all probabilities, still awaiting completion. Of course, I recognized it instantly, and began to cast about in my mind for some means of making the necessary examination without disclosing my suspicions. For you will realize that I was unwilling to say anything to you about Stella's death until the question was settled one way or the other. If the examination had shown no arsenic either in the candle or in the hair, it would not have been necessary to say anything to you at all.

  "But while I was debating the matter, the problem solved itself. As soon as I came to look at Stella's unfinished works, I saw that they cried aloud to be completed and that Polton was the proper person to carry out the work. I made the suggestion, which I should have made in any case, and when you adopted it, I decided to say nothing but to apply the tests when the opportunity offered."

  "I am glad," said I, "to hear you say that you would have made the suggestion in any case. It looked at first like a rather cold-blooded pretext to get possession of the things. But you were speaking of the hair. Can you depend on finding recognizable traces of arsenic in the hair of a person who has been poisoned?"

  "Certainly, you can," he replied. "The position is this: when arsenic is taken it becomes diffused throughout the whole body, including the blood, the bones and the skin. But as soon as a dose of arsenic is taken, the poison begins to be eliminated from the body, and, if no further dose is taken, the whole of the poison is thrown off in a comparatively short time until none remains in the tissues—with one exception. That exception is the epidermis, or outer skin, with its appendages—the finger and toe nails and the hair. These structures differ from all others in that, instead of growing interstitially and being alive throughout, they grow at a certain growing-point and then become practically dead structures. Thus a hair grows at the growing-point where the bulb joins the true skin. Each day a new piece of hair is produced at the living root, but when once it has come into being it grows no more, but is simply pushed up from below by the next portion. Thenceforward it undergoes no change, excepting that it gradually moves upwards as new portions are added at the root. It is virtually a dead, unchanging structure.

  "Now suppose a person to take a considerable dose of arsenic. That arsenic becomes diffused throughout all the living tissues and is for a time deposited in them. The growing-point of the hair is a living tissue and of course the arsenic becomes deposited in it. Then the process of elimination begins and the arsenic is gradually removed from the living tissues. But in twenty-four hours, what was the growing-point of the hair has been pushed up about the fiftieth of an inch and is no longer a growing structure. It is losing its vitality. And as it ceases to be a living tissue it ceases to be affected by the process of elimination. Hence the arsenic which was deposited in it when it was a living tissue is never removed. It remains as a permanent constituent of that part of the hair, slowly moving up as the hair grows from below, until at last it is snipped off by the barber; or, if the owner is a long-haired woman, it continues to creep along until the hair is full-grown and drops out."

  "Then the arsenic remains always in the same spot?"

  "Yes. It is a local deposit at a particular point in the hair. And this, Mayfield, is a most important fact, as you will see presently. For observe what follows. Hair grows at a uniform rate—roughly, a fiftieth of an inch in twenty-four hours. It is consequently possible, by measurement, to fix nearly exactly the age of any given point on a hair. Thus if we have a complete hair and we find at any point in it a deposit of arsenic, by measuring from that point to the root we can fix, within quite narrow limits, the date on which that dose of arsenic was taken."

  "But is it possible to do this?" I asked.

  "Not in the case of a single hair," he replied. "But in the case of a tress, in which all the hairs are of the same age, it is perfectly possible. You will see the important bearing of this presently.

  "To return now to my investigation. I had the bulk of a candle and a tress of Stella's hair. The questions to be settled were,

  "1. Was there arsenic in the candle? and

  "2. Had Stella been poisoned with arsenic?

  "I began by trimming the wax mould in readiness for casting and then I made an analysis of the trimmings. The result was the discovery of considerable quantities of arsenic in the wax.

  "That answered the first question. Next, as the tress of hair was larger than was required for your purpose, I ventured to sacrifice a portion of it for a preliminary test. That test also gave a positive result. The quantity of arsenic was, of course, very minute, but still it was measurable by the delicate methods that are possible in dealing with arsenic; and the amount that I found pointed either to one large dose or to repeated smaller ones.

  "The two questions were now answered definitely. It was certain—and the certainty could be demonstrated to a jury—that Stella had been poisoned by arsenic, and that the arsenic had been administered by means of poisoned candles. The complete proof in this case lent added weight to the less complete proof in the case of Monkhouse; and the two cases served to corroborate one another in pointing to Barbara as the poisoner. For she was the common factor in the two cases. The other persons—Wallingford, Madeline and the others—who appeared in the Monkhouse case, made no appearance in the case of Stella; and the persons who were associated with Stella were not associated with Monkhouse. But Barbara was associated with both. And her absence from home was no answer to the charge if death was caused by the candles which she had admittedly supplied.

  "But complete as the proof was, I wished, if possible, to make it yet more complete: to associate Barbara still more definitely with the crime. In the case of Monkhouse, it was clear that the poisoning always occurred when she wa
s absent from home. But this was not so clear in the case of Stella. Your diary showed that Stella's relapses coincided pretty regularly with Barbara's absences; but it was not certain (though obviously probable) that the relapses coincided with the periods of poisoning. It it could be proved that they did coincide, that proof would furnish corroboration of the greatest possible weight. It would show that the two cases were parallel in all respects.

  "But could it be proved? If the tress of Stella's hair had been at my disposal, I had no doubt that I could have decided the question. But the tress was yours, and it had to be preserved. Whatever was to be done must be done without destroying or injuring the hair, and I set myself the task of finding some practicable method. Eventually, I decided, without much hope of success, to try the X-rays. As arsenic is a fairly dense metal and the quantity of it in the deposits quite considerable, it seemed to me possible that it might increase the density of the hairs at those points sufficiently to affect the X-ray shadow. At any rate, I decided to give the method a trial.

  "Accordingly, Polton and I set to work at it. First, in order to get the densest shadow possible, we made the tress up into a close cylinder, carefully arranging it so that all the cut ends were in exactly the same plane. Then we made a number of graduated exposures on 'process' plates, developing and intensifying with the object of getting the greatest possible degree of contrast. The result was unexpectedly successful. In the best negative, the shape of the tress was faintly visible and was soon to be crossed by a number of perfectly distinct pale bands. Those bands were the shadows of the deposits of arsenic. There could be no doubt on the subject. For, apart from the fact that there was nothing else that they could be, their appearance agreed exactly with what one would have expected. Each band presented a sharp, distinct edge towards the tips of the hairs and faded away imperceptibly towards the roots. The sharp edge corresponded to the sudden appearance of arsenic in the blood when the poisoning began. The gradual fading-away corresponded to the period of elimination when the poisoning had ceased and the quantity of arsenic in the blood was becoming less and less from day to day.