The Clique of Gold by Emile Gaboriau

Thus proceeding from one point to another, and by the unaided power of his sagacity, coupled with indefatigable activity, the magistrate had succeeded in establishing Crochard's guilt, and the existence of accomplices who had instigated the crime. No one could doubt that he was proud of it, and that his self-esteem had increased, although he tried hard to preserve his stiff and impassive appearance. He had even affected a certain dislike to the idea of reading Henrietta's letter, until he should have proved that he could afford to do without such assistance.

But, now that he had proved this so amply, he very quickly asked for the letter, and read it. Like the chief surgeon, he, also, was struck and amazed by the wickedness of M. de Brevan.