“Alec, you are on your day to-day, aren’t you?” said Roger admiringly. “Precisely the same thought occurred to myself at a first glance. Then, looking carefully, as you so kindly suggest, I noticed that the indentation of the heel is very much deeper than that of the toe, indicating that somebody stepped backwards from the window to the ground, after thoughtfully closing the window behind him. If he’d been stepping up, the toe would be deeper than the heel, as a moment’s thought will show you, won’t it?”
“Oh!” said the crestfallen Alec.
“Sorry to have to score off you in that blatant Sherlockian way,” Roger continued more kindly, “but you did ask for it, you know. No, but seriously, Alec, this is most extraordinarily important. It clears up the last difficulty about murder.”
“But how did he close the window behind him?” asked Alec, still half incredulous.
“Oh! That’s the neatest thing of all. And delightfully simple, although it took me a minute or two to discover it after I’d seen the footprint. Look! You see this handle, the ordinary type for this sort of window. It consists of an arm that fits into the lock and a heavy handle set at right angles to it, the whole moving on a central pivot; the weight of the handle end keeps the other end in position. Well, watch!”
Carefully arranging the handle so that the heavy end was balanced exactly above the pivot, Roger pushed the window sharply back into its frame. Immediately the handle was dislodged by the jar, and, with a little click, the fastener fell into place in its socket, the weight of the falling handle driving it well home.
“Well, I’m dashed!” Alec said.
“Neat, isn’t it?” Roger said proudly. “He stood on the sill outside, you see, and pulled it to behind him, having fixed the handle in position before he got out. I suppose it’s a trick you could play with any lattice window, though I’ve never come across it before.”
“That’s one to you, all right,” said the humbled Alec. “I take back quite a lot of the unkind things I’ve said to you.”
“Oh, don’t trouble to apologise,” Roger said magnanimously. “Though I did warn you that I should turn out to be right in the end, you remember. Well, I don’t think you’ll trouble to dispute the fact of murder any more, will you?”