Outlaw Hunters

Amy Crawford in Smithsonian Magazine:

Allan Pinkerton was furious when he got the news. Joseph Whicher, a trusted agent of Pinkerton's National Detective agency, had been discovered in the Missouri woods, bound, tortured and shot dead—yet another victim of Jesse James, the outlaw whose gang Whicher had been assigned to track down. Not only outraged but humiliated by the failure, Pinkerton vowed to get James, declaring, "When we meet it must be the death of one or both of us."

Pinkerton dedicated his life to fighting criminals like Jesse James, and at one point was called the "greatest detective of the age" by the Chicago Tribune. For almost four decades, he and his agents captured bank robbers and foiled embezzlers. But Pinkerton had not set out to become America's original private eye; the humbly-born Scottish immigrant stumbled into crime-fighting.

More here.