Marianna and Momolo were not told that an illiterate, Catholic servant girl who had worked for the Mortara family "baptized" Edgardo five years before, when the child was sick. No one told Edgardo's parents that the servant girl "baptized" the infant when the parents were not in the room. No one told the Mortaras how the specific requirements of "the law" had been met. The shocked parents were only told they were losing their son forever.
No one told the parents, but someone told the Inquisitor. Allegedly in exchange for a dowry (money), the Inquisitor (Father Feletti) got the servant girl (Anna Morisi) to acknowledge the "facts" to him. Once she admitted baptizing Edgardo, Anna Morisi betrayed the family for whom she had worked. The Inquisitor's "investigation" was concluded. An order would be issued to the police. The police would "legally" take the child from his parents and his home.