Strategy and
Noireterre. The names of those he freed are written below his portrait, including Marie Salmon, referred to as "."|alt=Engraving of Pierre Noël Lecauchois by Cathelin and Noireterre. As part of their efforts to reverse Marie Salmon's conviction, Salmon's lawyers Pierre Noël Lecauchois and Jean-François Fournel wrote three () to argue Salmon's innocence and published them for the general public. Lecauchois wrote and , and Fournel wrote . The briefs were printed by Parisian publisher
André-Charles Cailleau. Lecauchois opened
Justification by recalling past victims of the unjust criminal code: The lawyers' goal in circulating these legal briefs was to sway public opinion in support of Salmon's innocence while also connecting her unjust victimization by the criminal justice system to the broader movement for judicial reforms at the time. In their briefs, they presented the rules of evidence and judicial process, challenging their audience of
laypersons to judge the circumstances for themselves, while also providing an emotionally compelling
first-person narrative from Salmon's perspective to "play up [her] candor and vulnerability." As Salmon narrates her story, "the reader is not allowed to forget for long that she is young, tender-hearted, and easily alluring."
Arguments Prejudiced investigation that dramatizes the court's recognition of Marie Salmon's innocence, Salmon stands alongside her lawyers Lecauchois and Fournel with her hands clasped in prayer, as they speak to a rapt gallery.|alt=An engraving prepared for Madame de Genlis that dramatizes the court's recognition of Marie Salmon's innocence. Both Pierre Noël Lecauchois and Jean-François Fournel raised issues with the investigation conducted by the prosecutor Roland Revel de Bretteville. In
Justification, Lecauchois accused Revel of deliberately conducting a hasty and flawed investigation. Lecauchois argued that Revel collected evidence days after the alleged crime, placed unfair weight on Madame Duparc's testimony against Salmon, neglected to interview key
persons of interest such as Madame Duparc's son, and did not consider testimonies that Salmon provided in her own defense. In
Consultation, Fournel described the past relationship that Revel had with Salmon shortly before her employment at the Duparc household, in which Revel tried to persuade her to move to Caen. According to Fournel, Revel held a deep grudge against Salmon after she had declined his invitation: While Fournel alludes to the "secret" nature of Revel's profound resentment by describing Salmon's beauty and youthfulness alongside Revel's initial "effusion" of benevolence, modern historians and
Sarah Maza state it plainly: Revel felt spurned after Salmon rejected his sexual advances.
Lack of evidence or motive Lecauchois argued that the police, surgeon, and lawyer who arrived at the Duparc home to investigate Beaulieu's death readily accepted the Duparc family's accusations against Salmon and possibly even
planted evidence against her. In one example, Lecauchois pointed out that when Marie Salmon was searched, a shiny white substance, believed to be poison, was found in her left pocket, but, notably, she never used that pocket because her left hand had been disabled since childhood (see
Early life). In
Consultation, Fournel directly accused the Duparc family of
framing Marie Salmon for the murder of Beaulieu. Lecauchois also argued that Salmon did not have any
motive to poison Beaulieu or anyone in the Duparc household. He noted that she did not know the Duparc family prior to working for them, and she had only spoken highly of her employment in the household prior to the Beaulieu's sudden illness and death. Furthermore, he pointed out that she maintained the composure of an innocent person by quickly consenting to searches and agreeing to appear before the king's prosecutor. The Duparc family, by comparison, behaved very differently. According to Salmon, the family did not grieve for Beaulieu; rather, they seemed "relieved" that he was dead.
Acquittal Lecauchois and Fournel's arguments were successful in winning Marie Salmon's freedom. On 23 May 1786, after over four years in prison, Salmon was fully acquitted of all charges. A large crowd waited outside the gates of in Paris to cheer for Marie Salmon and her lawyers Pierre Noël Lecauchois and Jean-François Fournel as they emerged. A witness and prolific journaler
Siméon-Prosper Hardy wrote about this moment: Afterwards, Salmon and Lecauchois had dinner at the home of their printer
André-Charles Cailleau. Hardy went to Cailleau's home and wrote that he witnessed crowds gathered in the street outside to watch Salmon through the first-floor windows. == Freedom and fame ==