In 2004, Thomas Hargrove, a 61-year-old retired news reporter from Virginia, became aware of the Federal Bureau of Investigation’s Uniform Crime Reporting (UCR) Supplementary Homicide Report and contemplated whether it was possible to teach a computer how to spot serial killers. He spent months trying to develop an algorithm that would identify unsolved cases with enough commonalities to suggest the same murderer. Hargrove eventually founded the Murder Accountability Project (MAP), a small nonprofit seeking to make FBI murder data more widely and easily available. MAP has already assembled case details on 638,454 homicides from 1980 through 2014, including 23,219 cases that had not been reported to the FBI. This is the most complete list of case-level details of U.S. murders available anywhere, and the group’s Web site has made it available at no cost to anyone with statistical analysis software.