In February 2002, New York Times Magazine writer Michael Finkel received a startling piece of news: a young man named Christian Longo, wanted for killing his entire family, had been captured in Mexico, where he'd taken on a new identity: Michael Finkel of the New York Times. The next day, on page A-3 of the Times, came another troubling item: a note from the editors explaining that Finkel, having falsified parts of an investigative article,...