'Stolen' years

When he tells the story - and he's told it more times than he can remember - his face contorts. Sometimes, the tears come, or the laughter. Sometimes, it's flashes of anger.

"This is what they did to me," he'll say, an apology of sorts for his inability to control his emotions.

The short version of what happened to Guy Gordon Marsh is this: In 1973, he was tried and convicted of first-degree murder in the killing of a customer inside a Glen Burnie 7-Eleven. A judge sentenced him to life in prison.

The only real evidence against Mr. Marsh, then 26, was the testimony of Linda Packech, a heroin addict who said she saw...