"When I got here," the detective said, "I decided on the theory of murder to make a careful search as soon as
day broke. I didn't have to wait for day, though, to find one crying piece of evidence. For a long time I was
alone in the room with the body. Queer feeling about that room, Mr. Graham. Don't know how to describe it
except to say it's uncomfortable. Too old, maybe. Maybe it was just being there alone with the dead man
before the dawn, although I thought I was hardened to that sort of thing. Anyway, I didn't like it. To keep my
spirits up, as well as to save time, I commenced searching the place with a candle. Nothing about the bed.
Nothing in the closets or the bureau."
He grinned sheepishly.
"You know I kind of was afraid to open the closet doors. Then I got on my knees and looked under the bed.
The light was bad and I didn't see anything at first. After a minute, close against the wall, I noticed something
white. I reached in and pulled it out. It was a handkerchief, and it had a monogram, Mr. Graham--R. B. in
purple and green."
He paused. Graham exclaimed sharply. Bobby felt the net tighten. If that evidence was conclusive to the
others, how much more so was it for him! He recalled how, after awaking in the empty house, he had searched
unsuccessfully in all his pockets for his handkerchief, intending to brush the dirt from his shoes.
"I went to his room," the detective hurried on, "and found a lot of his clothes and his stationery and his toilet
articles marked with the same cipher. I knew my man had made a big mistake--the sort of mistake every
criminal makes no matter how clever he is--and I had him. But that isn't, by any means, all. Don't look so
distressed, Mr. Graham. There isn't the slightest chance for him. You see I repaired the lock, and, as soon as it
was day, closed the room and went outside to look for signs. Since nightfall no one had come legitimately
through the court except Doctor Groom and myself. Our footprints were all right--making a straight line along
the path to the front door. In the soft earth by the fountain I found another and a smaller print, made by a very
neat shoe, sir, and I said to myself: 'There is almost certainly the footprint of the murderer.'
"There were plenty of others coming across the grass. He'd evidently avoided the path. And there was one
directly under the open window where the body lies. It's still there. Perhaps you can see it. No matter. That's
the last one I found. The prints ceased there. There wasn't a one going back, and I was fair up a stump. Then I
saw a little undefined sign of pressure on the grass, and I got an idea. 'Suppose,' I says, 'my man took his shoes
off and went around in his stockinged feet!' I couldn't understand, though, why he hadn't thought of that
before. I went back to Robert Blackburn's room and got one of his shoes, and ran into a snag again. The sole
of the shoe was a trifle larger than the footprints. Every one of his shoes I tried was the same way. I argued
that the handkerchief was enough, but I wanted this other evidence. I simply had to clear up these queer
footprints.
"I figured, since the murder had been made to look so much like a natural death, that he'd come out here some
time to-day, expecting to carry it off. I wanted to go to the station, anyway, to find out if he'd been seen
coming through last night or early this morning. While I was talking to the station agent I had my one piece of
luck. I couldn't believe my eyes. Mr. Robert walks up from the woods. He'd been hiding around the
neighbourhood all the time. Probably had missed his handkerchief and decided he'd better not take any
chances. Yet it must have seemed a pretty sure thing that the station wouldn't be watched, and it's those nervy
things, doing the obvious, that skilful criminals get away with all the time. I needed only one look at him, and
I had the answer to the mystery of the footprints. I gave him plenty of time to come here and change his
clothes, then I manoeuvered him out of his room and went there and found the pumps he'd worn last night and
to-day. You see, they'd be a little smaller than his ordinary shoes. Not only did they fit the footprints exactly,
but they were stained with soil exactly like that in the court. There you are, sir. I've made a plaster cast of one
of the prints. I've got it here in my pocket where I intend to keep it until I clear the whole case up and turn in
my report."