He lowered his voice. “Fingerprints!” He stood off a few steps to judge of his effect. “Yes,” I said mildly. “I guessed that.” I do not see why I should be supposed to be totally devoid of intelligence. After all, I read detective stories, and the newspapers, and am a man of quite average ability. If there had been toe marks on the dagger handle, now, that would have been quite a different thing. I would then have registered any amount of surprise and awe.