The Man Who Catches Marathon Cheats—From His Home

For months, a runner named Cindy posted motivational photos on Instagram and Facebook, chronicling the miles she put in to prepare for the New York Marathon. Cindy ran the race of her life, finishing the New York Marathon in just 3 hours 17 minutes and 29 seconds—a lot faster than her pace in previous half-marathon finishes, which each took a little over two hours.

“Ran my heart out ...