Banker Sitting in U.S. Prison Has a Most Incredible Tale to Tell

Eugene Gourevitch, a 39-year-old University of California, Berkeley-educated finance whiz, spends his days working in the library in a federal prison in Montgomery, Ala.

He is serving a five-year sentence for wire fraud related to insider trading.

How Gourevitch ended up as an inmate is no run-of-the-mill Wall Street tale of a promising career gone awry. It’s a story so snarled that it borders on the absurd, part pulp thriller, part black comedy. And it shows what can happen when the government is stuck relying on a crafty opportunist.

Tangled though his story may be, this seemingly dream informant could be ...