window lighting the hall, which was large; beyond those windows again, on each side, there were glass doors opening to the ground and protected by the ordinary green latticed shutters of wood, which now stood hooked back against the wall.  These glass doors opened into rooms oblong in shape, which ran through towards the back of the house, and were lighted in addition by side windows.  The room upon the extreme left, as the party faced the villa, was the dining-room, with the kitchen at the back; the room on the right was the salon in which the murder had been committed.  In front of the glass door to this room a strip of what had once been grass stretched to the gravel drive.  But the grass had been worn away by constant use, and the black mould showed through.  This strip was about three yards wide, and as they approached they saw, even at a distance, that since the rain of last night it had been trampled down.

“We will go round the house first,” said Hanaud, and he turned along the side of the villa and walked in the direction of the road.  There were four windows just above his head, of which three lighted the salon, and the fourth a small writing-room behind it.  Under these windows there was no disturbance of the ground, and a careful investigation showed conclusively that the only entrance used had been the glass doors of the salon facing the drive.  To that spot, then, they returned.  There were three sets of footmarks upon the soil.  One set ran in a distinct curve from the drive to the side of the door, and did not cross the others.

“Those,” said Hanaud, “are the footsteps of my intelligent friend, Perrichet, who was careful not to disturb the ground.”

Perrichet beamed all over his rosy face, and Besnard nodded at him with condescending approval.

“But I wish, M. le Commissaire”—­and Hanaud pointed to a blur of marks—­“that your other officers had been as intelligent.  Look!  These run from the glass door to the drive, and, for all the use they are to us, a harrow might have been dragged across them.”

Besnard drew himself up.

“Not one of my officers has entered the room by way of this door.  The strictest orders were given and obeyed.  The ground, as you see it, is the ground as it was at twelve o’clock last night.”

Hanaud’s face grew thoughtful.

“Is that so?” he said, and he stooped to examine the second set of marks.  They were at the righthand side of the door.  “A woman and a man,” he said.  “But they are mere hints rather than prints.  One might almost think—­” He rose up without finishing his sentence, and he turned to the third set and a look of satisfaction gleamed upon his face.  “Ah! here is something more interesting,” he said.