LOUISVILLE, Ky. — As disbarred lawyer Eric Conn sits in a federal prison, hundreds of people in one of America’s poorest regions remain mired in the legal mess he caused by running a $600 million fraud, the largest Social Security scam in U.S. history.Many of Conn’s former clients in eastern Kentucky’s Appalachian mountains, who counted on him for help getting their disability benefits, could again lose their monthly support.About 1,700 people already went through hearings to prove their …