Sex trafficking is big business. Globally, it generates tens of billions of dollars in profit every year. Here in the United States, it ensnares hundreds of thousands of victims. And while the stereotypical image of a trafficking victim is a foreign national, many of the exploited are underage American girls.

By the time Nassar was sentenced to 60 years in federal prison, his accusers numbered in the hundreds⁠—mostly athletes training and competing under the auspices of USA Gymnastics.

Christopher Bernard Wilder became known as 'The Beauty Queen Killer' during a frenzied 1984 spree, where he criss-crossed the U.S., luring young women into his fancy cars and dangling the promise of work as a model, if they would just allow him to take their photographs. Some took the bait. Others, he took by force.

Dominick Polifrone gained the confidence of the contract killer in an undercover operation that almost cost him his life.

For nearly two decades, Chicago faced a curious rise in the number of unsolved murders against women involving strangulation—all in certain areas of the city. We take a look at one of the unsolved cases and what police are doing to solve the string of murders.

For years, her name was treated as a shorthand joke: Lorena Bobbitt, the angry, crazy wife, a 22-year-old Ecuadorian immigrant who had cut off her husband John Wayne Bobbitt's penis with a kitchen knife while he slept in their Northern Virginia home. The June 1993 incident served as international tabloid fodder for months.

Rickey Ray Rector always had a troubled mind—as an adolescent, he fought regularly with peers, and by 17, he was a career criminal. But over the course of four days, his disturbing behavior reached its peak when Ray shot five people with a .38-caliber pistol.

In a murder that shocked New York City in December 2010, Sylvie Cachay, a rising swimwear designer, was murdered at a members-only club by her unemployed boyfriend.

The idea that people have a right to defend themselves—even using force that would otherwise be illegal—harks back centuries and formed the basis of the American legal system. We navigate the murky and still-evolving world of self-defense laws in the U.S.

We speak with Christopher Kuvlesky, an agent with the Investigative Services Branch (ISB) of the National Park System about what it's like investigating violent crimes within our vast national parks.