"You were talking about the chair," Colin reminded him.
"Yes, it's odd that it should have been there, but I can't see that it has any real bearing on the actual crime. Though if my explanation is right, the police would have found the murderer's prints on it, though not Ena Stratton's. I'm sorry, by the way, to keep on using that term for the poor fellow who retorted on her at last in the only possible way, but there doesn't seem to be another. Executioner is too formal."
"David," said Colin carefully, "actually admitted it to you?"
"Oh, no. He didn't try, and I wouldn't have let him if he had. It just went tacitly, by default. But Ronald did."
"Ronald told you he and David had done it?"
"No, no. Ronald apparently had no hand in it. He doesn't appear to be in the least worried about his alibi. But he knows David did it. He told me with some care that David hasn't said a word to him, or he to David; but he knows all right, and I should imagine that David knows he knows. But Ronald and I took some time in explaining elaborately to each other that neither of us does know anything, and doesn't intend to; so that's all quite satisfactory."
"And the police don't know?"
"No, that's our great consolation. And that's what we've got to build on. Let's try to reconstruct their ideas. They can't possibly know even that murder has been committed at all, let alone who did it. They may remotely suspect, but all they actually know is that there has been some hanky - panky going on. Some interested party wiped that chair clear of fingerprints; and not just the back, but the sides and seat and everything. You did wipe the seat, didn't you?"
"I polished the blessed seat!" groaned Colin.
"Don't be unhappy. It's a very good thing you did. Don't you see that with a wooden seat like that, not only fingerprints but traces of footprints would be looked for? The suicide theory involves Mrs. Stratton having stood on a chair. Well, with modern methods of detection it would be perfectly simple to establish whether anyone had or had not stepped recently onto the seat of that chair from this roof. The surface of the asphalt is covered with flint; quite a large amount of it would be carried up onto the seat of the chair and pressed firmly into the varnish, and even into the wood, by the weight of the person. The knocking over the chair would displace some, but not all; and the traces of what had been displaced would be quite visible. A microscopic examination of the seat would tell all this as clearly as I've told it to you.
"And I'm not at all sure," added Roger uneasily, "that a microscopic examination even after the polishing you gave it won't show that Mrs. Stratton didn't stand on it at all. It's marvellous how accurate these expert witnesses are. Still, as you can understand, much better that you did polish than that you shouldn't have done."
"Well, come, that's something," said Colin, but he sounded more than a little uneasy, too.
"So what do we come to then? The police know that someone has been tinkering with that chair, with or without a criminal motive. And they may be pretty certain that Mrs. Stratton never stood on it at all. If they are, then undoubtedly there is going to be the devil to pay; because that proves murder. But even then, looking on the hopeful side, to prove murder isn't to prove a murderer; and though there certainly would be a nasty pother, and a great deal of unpleasantness all round, I'm not at all sure that David's neck would ever be seriously in danger. Even if the police were quite, quite sure he'd done it, there's so little real evidence in the case at all that they would have an exceedingly difficult job to prove it.
"However, that's the worst that can happen, and it may not; so let's leave that possibility out of the reckoning just now and concentrate on what is quite certain. Well, all that's really certain so far I think, is that the police feel that there is cause for further investigation. They've made photographic records of the appearance of the roof, and they're retaining all of us here in case they want to question us further. That's all quite normal, and not so very formidable after all."
"I'm glad to hear it," said Colin.
"But what I don't quite like is the removal of the body to the mortuary. It was inevitable, if the police weren't satisfied; but it means a postmortem - and goodness knows what that may reveal."
"But hang it all, man, the cause of death must be obvious enough?"
"Oh, the cause of death, yes. But that's not all they'll look for. There's the question of bruises, you see. I didn't ask Chalmers last night whether he'd looked for any bruises on the body, but I don't imagine he did. Or Mitchell. In a perfectly straightforward case they probably wouldn't. But now of course the man who does the p.m. will - and that may prove a little awkward."
"But why might there be bruises on the body?"
"Well, consider how it must have been done. I don't suppose Mrs. Stratton was persuaded quite peaceably to put her neck in the noose, while David gave her a friendly hoist, do you? How it was actually effected I can't say, and no doubt a certain amount of guile was employed as far as possible: but there must have been some kind of a last - second struggle. Not a long one, because, so far as we know, she never screamed; and I think she would have been heard if she did. I wonder," said Roger thoughtfully, "how the devil the man did succeed in getting it done so quietly. And so quickly. He can't have been more than three or four minutes over it, at the most, so far as I can work out the times. Though it is a little doubtful just when he got back into the ballroom."
"You always say," Colin remarked tentatively, "that the psychology of the murderer is a great help in reconstructing a crime. Couldn't that apply, too, to the psychology of the victim?"
"That's a very shrewd observation, Colin," said Roger with enthusiasm. "And it interests me particularly, because it reminds me of a remark I made last night about Ena Stratton, which sounded very profound, but which I thought, as soon as I'd made it, might not bear very much examination. Perhaps it was deeper than I suspected. In fact, Colin, I believe I made it to you. Do you remember my saying that something or other, I forget now what, was significant not only of everything that had happened to Mrs. Stratton so far, but of anything that might happen to her in the future?"
"Yes, I do remember. I wondered at the time what the deuce you meant."
"To tell you the truth, so did I. But I must have meant something, surely. You can't call to mind what the occasion was, I suppose?"
"Yes, I do. It was her exhibitionism."
"Ah, was it? I said her exhibitionism was significant of anything that might happen to her in the future; and what did happen was that she got murdered. Well, could her exhibitionism have been responsible for that? I don't quite see how."
"It was the time she climbed on that beam. Can you get anything out of that? Suppose she climbed up on the gallows, and wee David swarmed up after her?"
Roger laughed. "That's taking me a trifle too literally. But it's a possible idea, for all that. That's the trouble. Any extravagant idea in that line is possible with Mrs. Stratton. But I'm afraid that if your theory were right, and David had slipped the noose over her head on top of the gallows instead of underneath them, her neck would have been broken. And there's no question of that. She died from strangulation all right. The rope was much thicker and suffer than the ordinary hangman's rope, and the excoriations on her palms show that she tried to clutch at it, so she probably died more slowly; but her own movements would tighten the noose round her neck in a fairly short time. Still, you may not be so wide of the mark, Colin. It's certain, if we accept that there was no more than a very short struggle, as I think we can, that some kind of ruse was employed; and I've no doubt that Mrs. Stratton herself, and possibly her exhibitionism, dictated the ruse's nature. Still, that's beside the point. The trouble is that there must have been some violence used, if only at the last second; and violence always leaves traces.