Jean Le Maistre, Magistri, Dominican, bachelor of theology from some university other, than Paris, was vicar of the Inquisitor of France in the diocese of Rouen from 1424.

In 1431 we find him referred to as prior of the monastery of Preaching Brothers at Rouen, where he enjoyed a reputation as a preacher. He was still living at the time of the first investigations made at Rouen in Jeanne's Rehabilitation (he preached a sermon in January, 1452); but it is probable that he was dead by 1455. At any rate, he was not consulted nor cited in the course of the second Procès.

He has been represented, by later historians, as acting on the threats of Pierre Cauchon, and even as speaking on the irregularities of the Trial. In truth he was less zealous than Jean Graverent, the Grand Inquisitor of France, at that time detained at Coutances by another trial, who ordered La Maistre to join Jeanne's trial, and preached at Paris against remembrance of Jeanne.

Le Maistre reserved his opinion on the matter of torture; but he condemned the monk Pierre Bosquier, who spoke critically of Jeanne's sentence. On April 24, 1431, Jean Le Maistre received from the English government a gratuity Of 20 salus d'or "for his pains, labors and diligence in having been present and assisted at the trial."

He was, perhaps, simply a timid man, but entirely devoted to Cauchon, and but little convinced of the regularity of the Trial (at least according to the testimony of Nicolas de Houppeville). Jean de Maistre certainly hesitated in accepting the conduct of the business and he took the precaution of protecting himself behind the Inquisitor-general.

On December 7, 1443, however, he preached to the people on the occasion of the election of Raoul Roussel as Archbishop of Rouen, Roussel who was one of Jeanne's most English-minded judges, and successor to the Cardinal de Luxembourg.