Did you know that the U.S. National Parks Service has its own specialized investigative bureau called the Investigative Services Branch (ISB)? The 33 agents within its ranks investigate all serious crimes on National Parks land including rape, murder, and even child pornography.

At Outside, Rachel Monroe offers a fascinating profile of the members of the ISB and the lengths they go to see justice served, much to the chagrin of Harold Henthorn, who thought he’d get away with pushing his wife to her death off of a sheer, 150-foot cliff for the insurance payout. Agent Beth Shott caught the case and painstakingly unravelled the false cover of a man who was keeping a backpack full of secrets.

At first, the accident seemed tragic in a routine way; many people fall to their deaths in national parks every year. But over the next few days, as Faherty dug deeper into the case, several things struck him as strange. For instance, the timeline Harold gave didn’t line up with the evidence. And other details seemed off, too, like how Harold insisted he’d given his wife CPR, but Faherty recalled that her lipstick had been unsmudged when he arrived on scene. Faherty asked Harold about his previous marriage. His first wife had died in an accident, Harold said. He was reluctant to talk about it.

The elite special agents assigned to the ISB—the National Park Service’s homegrown equivalent to the FBI—are charged with investigating the most complex crimes committed on the more than 85 million acres of national parks, monuments, historical sites, and preserves administered by the National Park Service, from Alaska’s Noatak National Preserve to Hawai’i Volcanoes National Park. They have solved homicides, tracked serial rapists hiding in the backcountry, averted kidnappings, and interdicted thousands of pounds of drugs. They’ve busted a reality TV host who poached a grizzly bear and infiltrated theft rings trafficking in looted Native American artifacts. But the ISB remains relatively unknown to the general public and even to fellow law enforcement. Local cops and FBI agents are sometimes baffled when Yosemite-based ISB Special Agent Kristy McGee presents her badge in the course of an investigation. “They’ll say something like, ‘What do you guys investigate? Littering?’” she told me recently.

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