Before his departure Aubert had tried to persuade Mme. Gibon to sell up her son-in-law by claiming from him the unpaid purchase-money for her husband's shop. He represented Fenayrou as an idle gambler, and hinted that he would find her a new purchaser. Such an underhand proceeding was likely to provoke resentment if it should come to the ears of Fenayrou. During the two years that elapsed between his departure from Fenayrou's house and his murder, Aubert had prospered in his shop on the Boulevard Malesherbes, whilst the fortunes of the Fenayrous had steadily deteriorated.
At the end of the year 1881 Fenayrou sold his shop and went with his family to live on one of the outer boulevards, that of Gouvion-Saint-Cyr. He had obtained a post in a shady mining company, in which he had persuaded his mother-in-law to invest 20,000 francs. He had attempted also to make money by selling fradulent imitations of a famous table-water. For this offence, at the beginning of 1882, he was condemned by the Correctional Tribunal of Paris to three months' imprisonment and 1,000 francs costs.
In March of 1882 the situation of the Fenayrous was parlous, that of Aubert still prosperous.
Since Aubert's departure Mme. Fenayrou had entertained another lover, a gentleman on the staff of a sporting newspaper, one of Fenayrou's turf acquaintances. This gentleman had found her a cold mistress, preferring the ideal to the real. As a murderess Madame Fenayrou overcame this weakness.
If we are to believe Fenayrou's story, the most critical day in his life was March 22, 1882, for it was on that day, according to his account, that he learnt for the first time of his wife's intrigue with Aubert. Horrified and enraged at the discovery, he took from her her nuptial wreath, her wedding-ring, her jewellery, removed from its frame her picture in charcoal which hung in the drawing-room, and told her, paralysed with terror, that the only means of saving her life was to help him to murder her lover.
Two months later, with her assistance, this outraged husband accomplished his purpose with diabolical deliberation. He must have been well aware that, had he acted on the natural impulse of the moment and revenged himself then and there on Aubert, he would have committed what is regarded by a French jury as the most venial of crimes, and would have escaped with little or no punishment. He preferred, for reasons of his own, to set about the commission of a deliberate and cold-blooded murder that bears the stamp of a more sinister motive than the vengeance of a wronged husband.
The only step he took after the alleged confession of his wife on March 22 was to go to a commissary of police and ask him to recover from Aubert certain letters of his wife's that were in his possession. This the commissary refused to do. Mme. Gibon, the mother-in-law, was sent to Aubert to try to recover the letters, but Aubert declined to give them up, and wrote to Mme. Fenayrou:
"Madame, to my displeasure I have had a visit this morning from your mother, who has come to my home and made a most unnecessary scene and reproached me with facts so serious that I must beg you to see me without delay. It concerns your honour and mine.... I have no fear of being confronted with your husband and yourself. I am ready, when you wish, to justify myself.... Please do all you can to prevent a repetition of your mother's visit or I shall have to call in the police."
It is clear that the Fenayrous attached the utmost importance to the recovery of this correspondence, which disappeared with Aubert's death. Was the prime motive of the murder the recovery and destruction of these letters? Was Aubert possessed of some knowledge concerning the Fenayrous that placed them at his mercy?
It would seem so. To a friend who had warned him of the danger to which his intimacy with Gabrielle Fenayrou exposed him, Aubert had replied, "Bah! I've nothing to fear. I hold them in my power." The nature of the hold which Aubert boasted that he possessed over these two persons remains the unsolved mystery of the case, "that limit of investigation," in the words of a French judge, "one finds in most great cases, beyond which justice strays into the unknown."