It was the only line of defence which remained open to him, and he clung to it, with the hope of imposing on the magistrates by redoubled hypocrisy and pious observances.  But all this laboriously constructed scaffolding of lies was shaken to its base and fell away piece by piece.  Every moment brought fresh and overwhelming revelations.  He professed that Madame de Lamotte had died suddenly in his house, and that, fearing suspicion, he had buried her secretly.  But the doctors called on to examine the body declared that she had been poisoned with corrosive sublimate and opium.  The pretended payment was clearly an odious imposture, the receipt a forgery!  Then, like a threatening spectre, arose another question, to which he found no reply, and his own invention turned against him.

Why, knowing his mother was no more, had he taken young de Lamotte to Versailles?  What had become of the youth?  What had befallen, him?  Once on the track, the cooper with whom he had lodged on the 12th of February was soon discovered, and an Act of Parliament ordered the exhumation of the corpse buried under the name of Beaupre, which the cooper identified by a shirt which he had given for the burial.  Derues, confounded by the evidence, asserted that the youth died of indigestion and venereal disease.  But the doctors again declared the presence of corrosive sublimate and opium.  All this evidence of guilt he met with assumed resignation, lamenting incessantly for Edouard, whom he declared he had loved as his own son.  “Alas!” he said, “I see that poor boy every night!  But it softens my grief to know that he was not deprived of the last consolations of religion!  God, who sees me, and who knows my innocence, will enlighten the magistrates, and my honour will be vindicated.”

The evidence being complete, Derues was condemned by sentence of the Chatelet, pronounced April 30th, and confirmed by Parliament, May 5th.  We give the decree as it is found in the archives: 

“This Court having considered the trial held before the Provost of Paris, or his Deputy-Lieutenant at the Chatelet, for the satisfaction of the aforesaid Deputy at the aforesaid Chatelet, at the request of the Deputy of the King’s Attorney General at the aforesaid Court, summoner and plaintiff, against Antoine-Francois Derues, and Marie-Louise Nicolais, his wife, defendants and accused, prisoners in the prisons of the Conciergerie of the Palace at Paris, who have appealed from the sentence given at the aforesaid trial, the thirtieth day of April 1777, by which the aforesaid Antoine-Francois Derues has been declared duly attainted and convicted of attempting unlawfully to appropriate without payment, the estate of Buissony Souef, belonging to the Sieur and Dame de Saint Faust de Lamotte, from whom he had bought the said estate by private contract on the twenty-second day of December 1775, and also of having unworthily abused the hospitality shown by him since the sixteenth day of December last