The Serial-Killer Detector (2017)

It also considers whether the rate of unsolved murders in a city is notable, since an uncaught serial killer upends a police department’s percentages. The F.B.I. believes that less than one per cent of the killings each year are carried out by serial killers, but Hargrove thinks that the percentage is higher, and that there are probably around two thousand serial killers at large in the U.S. “How do I know?” Studying the Social Security Administration’s Death Master File—“where we will all end up one day,” Hargrove said—he noticed that some people were included for a given year and dropped a few years later: people who had mistakenly been declared dead.

Source: www.newyorker.com