Papa Tignol knelt down as directed and examined the sofa seat, which was covered with a piece of Chinese embroidery.
"_Sapristi!_ You're a magician!" he cried in great excitement.
"No," replied Coquenil, "it's perfectly simple. These holes in the wall are five feet above the floor. And I'm enough of a carpenter, Papa Tignol," he smiled, "to know that a man cannot work an auger at that height without standing on something. And here was the very thing for him to stand on, a sofa just in place. So, _if_ Martinez bored these holes, he stood on this sofa to do it, and, in that case, the marks of his heels must have remained on the delicate satin. And here they are."
"Yes, here they are, nails and all," admitted Tignol admiringly. "I'm an old fool, but--but----"
Coquenil's face darkened. "Ah, that's the question. We'll know that when we talk to the woman."
The old man leaned forward eagerly: "_Why do you think the woman helped him?_"
"_Somebody_ helped him or the chips would still be there, _somebody_ held back those hangings while he worked the auger, and somebody carried the auger away."
Tignol pondered this, a moment, then, his face brightening: "Hah! I see! The sofa hangings were held back when the shot came, then they fell into place and covered the holes?"
"That's it," replied the detective absently.
"And the man in Number Seven, the murderer, lifted that picture from its nail before shooting and then put it back on the nail after shooting?"
"Yes, yes," agreed M. Paul. Already he was far away on a new line of thought, while the other was still grappling with his first surprise.
"Then this murderer must have _known_ that the billiard player was going to bore these holes," went on Papa Tignol half to himself. "He must have been waiting in Number Seven, he must have stood there with his pistol ready while the holes were coming through, he must have let Martinez finish one hole and then bore the other, he must have kept Number Seven dark so they couldn't see him----"
"A good point, that," approved Coquenil, paying attention. "He certainly kept Number Seven dark."
"And he _probably_ looked into Number Six through the first hole while Martinez was boring the second. I suppose _you_ can tell which of the two holes was bored first?" chuckled Tignol.