On the night of May 3, 2014, in the capital of Trinidad and Tobago, a federal prosecutor named Dana Seetahal sat before a slot machine. Gambling was her favorite form of relaxation and had become one of her only hobbies. Her days as a marathon runner had ended, and now the brainless churn of numbers on the screen felt like the most effective stress relief. She was a regular customer at the Ma Pau Casino, which was tucked into a row of bars and restaurants in the middle-class Woodbrook neighborhood of the city of Port of . . .