What constitutes historical truth is often subject to change. Through ingenious detection, the accepted wisdom of one generation may become the discredited legend of another -- or vice versa. In this wide- ranging study of historical investigation, former detective Joe Nickell allows the reader to look over his shoulder as he demonstrates the use of varied techniques in solving some of the world's most perplexing mysteries. All the major categories of historical mystery are here -- ancient riddles, biographical enigmas, hidden identity, "fakelore," questioned artifacts, suspect documents, lost texts, obscured sources, and scientific challenges. Each is then illustrated by a complete case from the author's own files. Nickell's investigation of the giant Nazca drawings in Peru, for example -- thought by some to provide proof of ancient extraterrestrial visitations -- uses innovative techniques to reveal a very different origin. Other cases concern the 1913 disappearance of writer and journalist Ambrose Bierce, the authenticity of the Shroud of Turin, the truth about the identity of John Demjanjuk ("Ivan the Terrible" to Polish death camp victims), the fate of a lost colonial American text, the authenticity of Abraham Lincoln's celebrated Bixby letter, and the apparent real-life model for a mysterious character in a novel by Nathaniel Hawthorne. In reaching his solutions, Nickell demonstrates a wide variety of investigative techniques -- chemical and instrumental analyses, physical experimentation, a "psychological autopsy," forensic identification, archival research, linguistic analysis, folklore study, and many others. His highly readable book will intrigue the scholar and the history buff no less than the mystery lover.