Unfortunately, the one and only indispensable proof was in Lupin's pocket. How was he to get hold of it?
Ganimard cast about, exhausted himself with fresh investigations, went over the inquiry from start to finish, spent sleepless nights in turning over the mystery of the Rue de Berne, studied the records of Prévailles' life, sent ten men hunting after the invisible sapphire. Everything was useless.
On the 28th of December, the examining-magistrate stopped him in one of the passages of the Law Courts:
"Well, M. Ganimard, any news?"
"No, monsieur le juge d'instruction."
"Then I shall dismiss the case."
"Wait one day longer."
"What's the use? We want the other end of the scarf; have you got it?"
"I shall have it to-morrow."
"To-morrow!"