Macé had one answer only, and that was Pierre Voirbo. The fellow had a very bad record, and his association with the secret police did not earn for him any prestige in the eyes of the law. He was a dissipated loafer, ready to betray friend and foe alike, and Macé was well aware that Voirbo was quite equal to murdering Bodasse for much less than ten thousand francs.
Yet the detective hesitated and it was only after tracing Italian securities belonging to the murdered man to Voirbo's possession that Macé decided to arrest him. Time had been lost in investigating certain clues suggested by Voirbo himself, but there could be little doubt now that they had been merely blinds to distract suspicion from himself. Voirbo must have realized that his position was growing worse every day. He had begun by affecting to despise Macé, but by now he knew that the young officer had proved himself to be a past-master in the art of detection.
By a coincidence the very morning appointed by Macé for Voirbo's arrest saw the suspected man walk into the detective's office, apparently quite unconscious of his fate. He had come, as usual, to offer his opinion on the great mystery, and to accuse more innocent men. Macé kept him waiting for half an hour, and when he eventually turned to speak to him Voirbo dropped a card from his pocket-book. Macé picked it up for him, and as he did so saw at a single glance that Voirbo had booked a passage on a ship leaving France, and had given a false name.
Ten minutes later Voirbo was under arrest. He swore that he was innocent, and reviled Macé horribly. But the detective was unmoved, although there was much to be accomplished before legal proof was forthcoming.
A visit was paid to Voirbo's wife, an innocent girl, whose heart was broken when she learned the truth. She produced the box where her and her husband's marriage dots were kept. Macé opened it, and showed that it was empty. He had robbed his wife as well as Bodasse.
The officer, however, was determined to find the securities Voirbo had stolen from Bodasse's room, and he began a thorough search. When he reached the cellar he found two casks of wine. A strict examination of these revealed a piece of black string tied to a bung above the head of one of the casks. Macé drew it out, and at the end found a thin metal cylinder, neatly soldered. Inside were the missing securities.
Another experiment remained. Voirbo was taken by the police to the room where it was suspected the crime had been committed. Here Macé had him forcibly seated in a chair, and in his presence the detective tested the slope of the floor by pouring water on it. The water instantly dribbled towards the bed, finally settling in a particular spot. The boards were taken up, and congealed blood found.
Macé had argued that during the murder of Bodasse much blood had been spilt, and that some of it must have sunk between the boards at a point where the slope had brought it to a standstill. Voirbo had washed the top of the boards, but had forgotten to wash underneath.
This simple experiment had such an effect upon Voirbo that he instantly confessed to the crime, telling everything without reservation. He did not, however, go to the guillotine, for before his trial, and after one abortive attempt to escape, he cut his throat in prison. The knife with which he took his own life was smuggled into the gaol concealed in a loaf, and although Macé strove valiantly to discover the person who had sent it to Voirbo he never succeeded.