Here Marlowe paused and walked to the oaken desk before the window. Opening a drawer full of miscellaneous objects, he took out a box of odd keys, and selected a small one distinguished by a piece of pink tape.
He handed it to Trent. "I keep that by me as a sort of morbid memento. It is the key to the lock I smashed. I might have saved myself the trouble if I had known that this key was at that moment in the left-hand side-pocket of my overcoat. Manderson must have slipped it in, either while the coat was hanging in the hall or while he sat at my side in the car. I might not have found the tiny thing there for weeks--as a matter of fact I did find it two days after Manderson was dead--but a police search would have found it in five minutes. And then I--I with the case and its contents in my pocket, my false name and my sham spectacles and the rest of it--I should have had no explanation to offer but the highly convincing one that I didn't know the key was there."
Trent dangled the key by its tape idly. Then--"How do you know this is the key of that case?" he asked quickly.
"I tried it. As soon as I found it I went up and fitted it to the lock. I knew where I had left the thing. So do you, I think, Mr. Trent. Don't you?" There was a faint shade of mockery in Marlowe's voice.
"Touché!" Trent said, with a dry smile. "I found a large empty letter-case with a burst lock lying with other odds and ends on the dressing-table in Manderson's room. Your statement is that you put it there. I could make nothing of it." He closed his lips.
"There was no reason for hiding it," said Marlowe. "But to get back to my story. I burst the lock of the strap. I opened the case before one of the lamps of the car. The first thing I found in it I ought to have expected, of course; but I hadn't." He paused and glanced at Trent.
"It was--" began Trent mechanically; and then stopped himself. "Try not to bring me in any more, if you don't mind," he said, meeting the other's eye. "I have complimented you already in that document on your cleverness. You need not prove it by making the judge help you out with your evidence."
"All right," agreed Marlowe. "I couldn't resist just that much. If _you_ had been in my place you would have known before I did that Manderson's little pocket case was there. As soon as I saw it, of course, I remembered his not having had it about him when I asked for money, and his surprising anger. He had made a false step. He had already fastened his note-case up with the rest of what was to figure as my plunder, and placed it in my hands. I opened it. It contained a few notes as usual--I didn't count them.