The following day, M. Denizet had Roubaud arrested. Strong in his almighty power, he had issued the warrant in one of those moments of inspiration, when he put faith in the genius of his perspicacity, and even before he had a sufficiently serious charge against the assistant station-master. In spite of the many obscure points that still remained, he guessed this man to be the pivot, the source of the double crime; and he triumphed at once when he seized a document making everything over to the survivor of the two, which Roubaud and Séverine had executed before Maître Colin, notary at Havre, a week after coming into possession of La Croix-de-Maufras. From that time the whole business became clear to his mind, with a certainty of reasoning, a strength of evidence which conveyed to the framework of the prosecution such indestructible solidity that the truth itself would have seemed less true, less logical, and tainted with more imagination. Roubaud was a coward, who, on two occasions, not daring to kill with his own hand, had made use of this violent brute Cabuche. The first time, being impatient to inherit from President Grandmorin, the terms of whose will he knew, and aware, moreover, of the rancour of the quarryman for this gentleman, he had pushed him into the coupé at Rouen, after arming him with a knife. Then, when the 10,000 frcs. had been shared, the two accomplices would perhaps never have met again, had not murder engendered murder. And it was here the examining-magistrate displayed that deep knowledge of criminal psychology which was so much admired, for he now declared that he had never ceased to keep an eye on Cabuche, his conviction being that the first murder would mathematically bring about another. Eighteen months had sufficed for this: the Roubauds were at sixes and sevens. The husband had lost the 5,000 frcs. at cards, while the wife had come to the point of taking a sweetheart to amuse herself. Doubtless she refused to sell La Croix-de-Maufras, in fear lest he should squander the money; perhaps in their continual quarrels she threatened to give him up to justice. In any case, the evidence of numerous persons established the absolute disunion of the couple, and here at last appeared the distant consequence of the first crime. Cabuche now comes forward again with his brutish instincts, and the husband, in the background, arms this man with the knife, to definitely ensure possession of this accursed house, which had already cost one human life, for himself. That was the truth, the appalling truth, everything led up to it: the watch discovered in the hut of the quarryman, and particularly the two corpses, both struck with the same identical blow in the throat, by the same hand, with the same weapon--that knife picked up in the room. Nevertheless, the prosecution had a doubt on this point. The wound of the President appeared to have been inflicted by a sharper and smaller blade.