The jury returned a verdict of suicide during temporary insanity, in accordance with this theory, and, to all outward appearances the case of Mr. Martin was disposed of. But Inspector Whyland, although relieved to feel that yet another unsolved crime had not been added to his already mounting debit account, knew well enough at heart that once again his mysterious adversary had scored a point against him. But again, there was this insoluble riddle of motive. It was possible to suggest more than one motive for the murder of Mr. Martin. He might, for instance, have fallen out with one of the jewel thieves with whom he had such intimate relations. Or again, his dealings with women might have been at the bottom of it. But, assuming one of these suppositions to be correct, how was the death of Mr. Martin to be linked with the previous murders? Or were they indeed all the work of separate persons, who imitated one another’s methods with a view to confusing the issue? Inspector Whyland recalled his mind from such unprofitable speculations. He felt that the solution of the whole mystery lay close under his hand, if he could but devise the means to unearth it. Somehow Mr. Copperdock’s name always came up in connection with these murders. He had been Tovey’s most intimate friend. The pipe which had been the cause of Colburn’s death had been bought at his shop. He must have been within a few yards of the scene when Pargent was murdered. And Whyland had no doubt that he would discover some point of contact between Mr. Copperdock and the present case. He was not disappointed. It came out, in the course of a conversation between him and Houlder, the builder. It seemed that Houlder, who was an occasional frequenter of the Cambridge Arms, had mentioned, early in the month, that a new tenant had taken Number 407, and that he had got the job of altering the premises for him. Mr. Copperdock had displayed great interest in this remark, and as a result Houlder had invited him to come and look over the place. Mr. Copperdock had accepted, and he and Houlder had been over every inch of it. This might have been pure curiosity on Mr. Copperdock’s part, but at least the fact was significant. Inspector Whyland stored it in the mental pigeon-hole which already contained the note that Martin and Copperdock had done considerable business together in the past.