After oil was discovered beneath their land in the 1920's, the richest people per capita were members of the Osage Indian nation in Oklahoma. They rode in chauffeured automobiles, built mansions and sent their children to study in Europe.
Then, one by one, the Osage began to be killed off. Many of those who dared to investigate the killings were themselves murdered. As thee death toll climbed to more than 24, the relatively new FBI took over. It was one of the organization's first major homicide cases but the bureau badly bungled the investigation. In desperation, the young director, J. Edgar Hoover, turned to a former Texas Ranger named Tom White to unravel the mystery, who put together an undercover team. Together with the Osage, they began to expose one of the most chilling conspiracies in American history.
We spoke with author David Grann about his investigation into the series of murders he said were done in cold blood.