When Kidnappings Were All the Rage: With panic in the air, federal law enforcement seized the moment.

• Author: Gulliver, Katrina

IN THE EARLY 1930s, FBI chief J. Edgar Hoover placed advertisements in newspapers advising the families of kidnapping victims to contact his agency. The ads encouraged them to telegraph or phone, since a letter would take too long. Berenice Urschel kept the number by the phone, just in case. When her oil magnate husband was abducted at gunpoint in 1933, she called immediately.

Her husband, Charles F. Urschel, was taken from his Oklahoma City home to a farmhouse in Texas, where he was held until a $200,000 ransom was paid. That was how most high-profile kidnappings turned out: pay the money, get home safe. But the Urschel kidnapping was the first where the FBI was involved from start to finish, thanks to the new Federal Kidnapping Act--a.k.a. "the Lindbergh Law."

St. Louis police chief Joseph Gerk estimated that there had been 3,000 kidnapping cases nationally in 1931. This was a ballpark figure, based on a survey of law enforcement agencies and an assumption that a large proportion were never reported to police. But whatever the right number was, the crime was common enough to capture the public imagination. "The New York Times began publishing 'Recent Kidnappings in America' as a regular feature, while Time magazine reported kidnappings along with notable births, deaths, and other milestones," the attorney Carolyn Cox writes in The Snatch Racket. "Lloyd's of London began underwriting kidnap insurance in the United States for persons of 'unquestioned reputation' who passed thorough background checks designed to eliminate those considered at risk of faking their own kidnappings."

Anxious parents had their children fingerprinted by the FBI, just in case, and hired guards for their houses. At the same time, across the country, two banks a day were being robbed. Crime seemed to be out of control.

Before the Federal Kidnapping Act took effect in 1932, kidnapping itself had not been a federal crime; it became one only if the victim was transported across state lines (or if the ransomers posted their demands, subjecting them to mail fraud laws). Of course, it wasn't always clear if a victim had been taken across state lines until after the kidnapping was resolved. Hoover saw an opportunity to extend his agency's remit, and plenty of legislators were ready to help him. The turning point came with the 1932 abduction of Charles Lindbergh's baby son.

In 1927, Lindbergh had piloted the first solo flight across the Atlantic Ocean, making him arguably...