All the traces of his presence had naturally been left during the first phase; the mutton-bone, the black footprints, the Basque cap, the handkerchief, the blood on the wall, on the door, and on the floor.

If those traces were still all there, they showed that Mademoiselle Stangerson--who desired that nothing should be known--had not yet had time to clear them away.

This led me to the conclusion that the two phases had taken place one shortly after the other.

She had not had the opportunity, after leaving her room and going back to the laboratory to her father, to get back again to her room and put it in order.

Her father was all the time with her, working.