On a warm Saturday evening in late May, Derek Murphy, wearing cargo shorts and a polo shirt, sat on his living room floor, his back against the couch, his legs stretched out, his computer on his lap. A baseball game was on the television, but Murphy, 49, wasn’t paying much attention to it. He was too busy scrolling through hundreds of photos and combing over data on his computer. Occasionally he’d stop to sip from a can of diet soda. During the week, Murphy, who lives outside of Cincinnati, worked as a data analyst for a health insurance company. But in his free time, he pursued an unusual hobby: exposing cheaters in endurance races.
Four years earlier, Murphy had started a website called Marathon Investigation, and recently he’d been looking…
