She appealed to François-Michel le Tellier, Marquis de Louvois claiming that she had information about other crimes of high importance.
Louvois reported to the King, who told Gabriel Nicolas de la Reynie, who, among other things, was the chief of the Paris police, to root out the poisoners.
Magdelaine de La Grange worked as a fortune teller after the execution of her husband for receiving stolen goods.
The marriage certificate proved to be a forgery issued by Abbé Nail, who had appeared as Faurye at the law clerk's office.
Magdelaine de La Grange and Abbé Nail were sentenced to death for forgery and murder on 4 February 1679, and four days later they were hanged.