“In short, Inspector Blaikie,” said the superintendent, half smiling, “you appear to hold very strong _prima facie_ evidence that each of these two men murdered the other.” The inspector groaned. “Don’t laugh at me, sir,” he said. “I’m doing my best to puzzle it out. Of course they didn’t kill each other. At least, both of them didn’t. They couldn’t. You know what I mean.” “You mean, I take it, that they could only have killed each other and left their bodies where they were found, on the assumption that at least one corpse was alive enough to walk about and commit a murder and then quietly replace itself where it had been killed. It will, I fear, be difficult to persuade even a coroner’s jury that such an account of the circumstances is correct.” “Of course it isn’t correct, sir; but you’ll admit that’s what it looks like. It is quite possible for a man who has committed a murder to be murdered himself as he leaves the scene of his crime; but it’s stark, staring nonsense for the man whom he has killed to get up, as if he were alive and well, and come after his murderer with a club. To say nothing of laying himself out again neatly afterwards. No, that won’t wash. Yet the evidence both ways is thoroughly good evidence.” “We can agree, inspector, that these two men did not kill each other. But it remains possible, even probable, on the evidence you have so far secured, that one of them did kill the other, and was then himself killed by some third person unknown, possibly a witness of the first crime bent on exacting retribution. How does that strike you?” The superintendent thrust his hands deep into his pockets and leant back in his chair with a satisfied look, as if he had scored a point. Inspector Blaikie’s face, however, hardly became less doleful. “Yes, that’s possible,” he said; “but unfortunately there is absolutely nothing to show which set of circumstantial clues ought to be accepted and which discarded in that case. We do not know which of the two men was killed first. When Brooklyn went to see Prinsep, did he murder him then and there in the study, or did Prinsep decoy his visitor into the garden by means of the note we have found, and there kill him? Either theory fits some of the facts: neither fits them all. I don’t know which to think, or which to work on as a basis. The evidence we have probably points in the right direction in one of the cases, and in the wrong direction in the other; but how are we to tell which is right and which is wrong? There is nothing to lay hold of.” “What about the medical evidence as to the time of death? Does that throw any light on the case?” “None whatever, unfortunately. In both instances the doctors agree that death almost certainly took place at some time between 10.30 and 12 o’clock. But they say it is impossible to time the thing any more accurately than that.” “Come, that seems at least to narrow the field of inquiry. When were each of these men last seen alive?”