So admirably had the accident been contrived that even Fairfield never suspected that it was anything but genuine. In a public telephone-box, a few hundred yards away, Heldon Foyle was examining the half-sheet of notepaper side by side with the photograph of the finger-prints on the dagger. A telephone-box is admirably constructed for the private examination of documents if one's back is towards the door and one is bent over the directory. Line by line Foyle traced "laterals," "lakes," and "accidentals," calling to his aid a magnifying glass from his waistcoat pocket. When he emerged he was rubbing his chin vigorously. The prints were totally different. Sir Ralph Fairfield was not the murderer of the man so astoundingly like Robert Grell. CHAPTER X The evidence of the finger-prints was entirely negative. Though Foyle believed that Fairfield was innocent, he never permitted himself to be swayed by his opinions into neglecting a possibility. It was still possible that the baronet might have been concerned in the crime even though they were some one else's prints on the dagger. At any rate Fairfield was suppressing something. It could do no harm to continue the watch that had been set upon him. So Foyle left Green and his companion to continue their unobtrusive vigil. To justify his stay in the box--for he was artist enough to do things thoroughly even though it might be unnecessary--he lifted the receiver and put a call through to Scotland Yard. "This is Foyle speaking," he said when at last he had got the man he asked for. "Is there anything fresh for me?" "Nothing important, sir, except that Blake has found a curiosity dealer who says that the knife is one that must have come from South America. It is, he says, an unusual sort of Mexican dagger." "Oh. Is the man who says that to be relied on? He isn't just guessing? We can do all the guessing we want ourselves." "No, sir, we think he's all right. It's Marfield--one of the biggest men in the trade. By the way, sir, there's a lot of newspaper men been asking for you since you left. They want to know about Goldenburg." "So do I," retorted the other. "You'd better be strictly truthful with 'em, Mainland. Tell 'em you know no more than is on the reward bill. They won't believe you, anyway. You can say I've gone home to bed, and that there will be nothing more doing this evening. Good-bye." "A Mexican dagger," he muttered to himself as he left the telephone-box. "Now, if I were a story-book detective I should assume that the murderer was either a South American or had travelled in South America. It looked the kind of thing a woman might carry in her garter. And a veiled woman called on him that night"--he made a wry face. "Foyle, my lad, you're assuming things. That way madness lies. The dagger might have been bought anywhere as a curiosity, and the veiled woman may have been a purely innocent caller."