Invitation to an Execution

Lloyd Schlup awaits death even though he has new evidence of his innocence

Sean O'Brien is the sort who calls a hooker "ma'am." His wife admits he deals with "the most awful people." Serial killers, murderers, thugs and the like. "With some," he says, "you have to dig a little deeper to find the good in them." But O'Brien, 37, is the sort of lawyer who will drive 300 miles across Missouri from his home in Kansas City to see clients. Especially those on death row. Especially if he believes they're innocent.

This week O'Brien is sweating out the case of Lloyd Schlup, 32, a man who has been in prison for nearly half...