When I spoke with Madame Precieuse, she showed me her hysterectomy scar and the Protestant church where she worships, but she told me that she had nothing to do with voodoo, nothing to do with zombies, nothing to do with magic, and nothing to do with Nadathe Joassaint. This may or may not be true, but that's what she told me.
In the absence of more information from Madame Precieuse, it's necessary to reconstruct the events from the statements of others and their claims of what transpired. According to Mano's testimony, he and Overne were passing through Carrefour Charles with Nadathe's zombie when they encountered Madame Precieuse, who demanded to see their travel documents. (Madame Zicot thinks Madame Precieuse must have approached them because she recognized Nadathe.) Every zombie is made only with the official approbation of the secret society; lacking these documents, the zombie is illicit. (These documents do exist: I was later able to examine a zombie laissez-passer.) Nadathe had no documents. This gave Madame Precieuse grounds to seize the zombie, as she was a great queen within the society, hierarchically superior to Mano and Overne.
But, assuming the story to be true, seizing the zombie would have put Madame Precieuse in a very difficult position, for the rules of the secret society were strict. I later discussed this with various members of the society, who explained to me that Madame Precieuse no more had the appropriate documents to possess and transport a zombie than Mano and Overne did, and by holding the zombie she would risk the harsh punishment of the law and the wrath of other sorcerers. Madame Precieuse might even have feared that she might be zombified herself, for having held the zombie illegally. Thus she apparently conceived her plan: to convince Mano to take Nadathe back to her mother, without ever admitting any involvement in this affair.
But that plan seems to have gone doubly awry. First, Madame Zicot revealed the private conversation between the two cousins to Judge Etienne, thus involving Madame Precieuse with the judicial system. Then, Mano did what no member of a secret society should ever do: He spoke publicly of the "affairs of the night."
When Judge Etienne arrested Madame Precieuse, relations between the two cousins were ruptured. Madame Precieuse blamed her cousin for her disgrace and humiliation – and Madame Zicot's best chance for recovering her daughter's zombie was lost.