His investigations, however, told him no more than he had learned before. The three dormer windows in the home next door gazed vacantly down at him, their windows covered with cobwebs and dust. The impossibility of anyone making their way from even the nearest of them, to the window where he stood, was manifest. And that a long rod or pole could have been utilized to introduce the letters into the girl's room was even more impossible. He shook his head, then turned to the other window, that facing upon the fire escape. Here, as on the occasion of his previous examination, the smooth glossy surface of the freshly dried paint showed no marks, except those he had himself made during his former visit. And yet, as his eyes searched the grated surface, he saw that there was something there, something that had not been there before. He reached out and picked it up. It was a woman's handkerchief, a tiny square of lace-edged linen, of an inexpensive variety. But it was not the mere presence of the handkerchief that so interested him. It might readily have belonged to Miss Morton herself, and have been accidentally dropped from the window. There were two things about this particular handkerchief, however, that marked it as a clue of the utmost value. One was the fact that in its corner was embroidered an initial, the letter "F." The other was that two of the corners of the handkerchief were knotted together, as though it had been tied about someone's wrist, for what reason, he could not imagine.