But the day of retribution was at hand, and a terrible mischance brought the murders to light. The nature of the poisons compounded by Salute Croix was so deadly, that, when working in his laboratory, he was obliged to wear a mask, to preserve himself from suffocation. One day, the mask slipped off, and the miserable wretch perished in his crimes. His corpse was found, on the following morning, in the obscure lodging where he had fitted up his laboratory. As he appeared to be without friends or relatives, the police took possession of his effects. Among other things was found a small box, to which was affixed the following singular document:—
"I humbly beg, that those into whose hands this box may fall, will do me the favour to deliver it into the hands only of the Marchioness de Brinvilliers, who resides in the Rue Neuve St. Paul, as everything it contains concerns her, and belongs to her alone; and as, besides, there is nothing in it that can be of use to any person but her. In case she shall be dead before me, it is my wish that it be burned, with everything it contains, without opening or altering anything. In order that no one may plead ignorance, I swear by the God that I adore, and by all that is held most sacred, that I assert nothing but the truth: and if my intentions, just and reasonable as they are, be thwarted in this point by any persons, I charge their consciences with it, both in this world and that which is to come, in order that I may unload mine. I protest that this is my last will. Done at Paris, the 25th of May, 1672.
"(Signed) Sainte Croix."
This earnest solicitation, instead of insuring respect as was intended, excited curiosity. The box was opened, and found to contain some papers, and several vials and powders. The latter were handed to a chemist for analysis, and the documents were retained by the police, and opened. Among them was found a promissory note of the Marchioness de Brinvilliers, for thirty thousand francs, to the order of Sainte Croix. The other papers were of greater importance, as they implicated both her and her servant, La Chaussee, in the recent murders. As soon as she was informed of the death of Sainte Croix, she made an attempt to gain possession of his papers and the box; but, being refused, she saw that there was no time to be lost, and immediately quitted. Next morning the police were on her trail; but she succeeded in escaping to England. La Chaussee was not so fortunate. Altogether ignorant of the fatal mischance which had brought his villanies to light, he did not dream of danger. He was arrested and brought to trial: being put to the torture, he confessed that he had administered poison to the Messieurs d'Aubray, and that he had received a hundred pistoles, and the promise of an annuity for life, from Sainte Croix and Madame de Brinvilliers, for the job. He was condemned to be broken alive on the wheel, and the Marchioness was, by default, sentenced to be beheaded. He was executed accordingly, in March 1673, on the Place de Greve, in Paris.
La Brinvilliers appears to have resided for nearly three years in England. Early in 1676, thinking that the rigour of pursuit was over, and that she might venture to return to the Continent, she proceeded secretly to Liege. Notwithstanding her care, the French authorities were soon apprised of her return; and arrangements were promptly made with the municipality of that city, to permit the agents of the French police to arrest her within the limits of their jurisdiction. Desgrais, an officer of the marechaussee, accordingly left Paris for that purpose. On his arrival in Liege, he found that she had sought shelter within the walls of a convent. Here the arm of the law, long as it is said to be, could not reach her: but Desgrais was not a man to be baffled, and he resorted to stratagem to accomplish what force could not. Having disguised himself as a priest, he sought admission to the convent, and obtained an interview with La Brinvilliers. He said, that being a Frenchman, and passing through Liege, he could not leave that city without paying a visit to a lady whose beauty and misfortunes were so celebrated. Her vanity was flattered by the compliment. Desgrais saw, to use a vulgar but forcible expression, "that he had got on the blind side of her;" and he adroitly continued to pour out the language of love and admiration, till the deluded Marchioness was thrown completely off her guard. She agreed, without much solicitation, to meet him outside the walls of the convent, where their amorous intrigue might be carried on more conveniently than within. Faithful to her appointment with her supposed new lover, she came, and found herself, not in the embrace of a gallant, but in the custody of a policeman.
Her trial was not long delayed. The proofs against her were abundant. The dying declaration of La Chaussee would have been alone enough to convict her; but besides that, there were the mysterious document attached to the box of St. Croix; her flight from France; and, stronger and more damning proof than all, a paper, in her own handwriting, found among the effects of St. Croix, in which she detailed to him the misdeeds of her life, and spoke of the murder of her father and brothers, in terms that left no doubt of her guilt. During the trial, all Paris was in commotion. La Brinvilliers was the only subject of conversation. All the details of her crimes were published, and greedily devoured; and the idea of secret poisoning was first put into the heads of hundreds, who afterwards became guilty of it.
On the 16th of July 1676, the Superior Criminal Court of Paris pronounced a verdict of guilty against her, for the murder of her father and brothers, and the attempt upon the life of her sister. She was condemned to be drawn on a hurdle, with her feet bare, a rope about her neck, and a burning torch in her hand, to the great entrance of the cathedral of Notre Dame; where she was to make the amende honorable, in sight of all the people; to be taken from thence to the Place de Greve, and there to be beheaded. Her body was afterwards to be burned, and her ashes scattered to the winds.
After her sentence, she made a full confession of her guilt. She seems to have looked upon death without fear; but it was recklessness, not courage, that supported her. Madame de Sevigne says, that when on the hurdle, on her way to the scaffold, she entreated her confessor to exert his influence with the executioner to place himself next to her, that his body might hide from her view "that scoundrel, Desgrais, who had entrapped her." She also asked the ladies, who had been drawn to their windows to witness the procession, what they were looking at? adding, "a pretty sight you have come to see, truly!" She laughed when on the scaffold, dying as she had lived, impenitent and heartless. On the morrow, the populace came in crowds to collect her ashes, to preserve them as relics. She was regarded as a martyred saint, and her ashes were supposed to be endowed, by Divine grace, with the power of curing all diseases. Popular folly has often canonised persons whose pretensions to sanctity were extremely equivocal; but the disgusting folly of the multitude, in this instance, has never been surpassed.
Before her death, proceedings were instituted against M. de Penautier, treasurer of the province of Languedoc, and Receiver-general for the clergy, who was accused by a lady, named St. Laurent, of having poisoned her husband, the late Receiver-general, in order to obtain his appointment. The circumstances of this case were never divulged, and the greatest influence was exerted to prevent it from going to trial. He was known to have been intimate with Sainte Croix and Madame de Brinvilliers, and was thought to have procured his poisons from them. The latter, however, refused to say anything which might implicate him. The inquiry was eventually stifled, after Penautier had been several months in the Bastille.
The Cardinal de Bonzy was accused by the gossips of the day of being an accomplice of Penautier. The Cardinal's estates were burthened with the payment of several heavy annuities; but, about the time that poisoning became so fashionable, all the annuitants died off, one after the other. The Cardinal, in talking of these annuitants, afterwards used to say, "Thanks to my star, I have outlived them all!" A wit, seeing him and Penautier riding in the same carriage, cried out, in allusion to this expression, "There go the Cardinal de Bonzy and his star!"