Captain Atom

A United States Air Force officer during the Vietnam War
Framed for a crime he didn't commit & sentenced to death
Participate in a military experiment, promised a presidential pardon
The alien metal, Dilustel, bonded to his skin, threw him forward in time twenty years
Current government refused to acknowledge the previous administration's promise;
Used his charges to blackmail him into being a government-controlled superhero
Reluctantly served the government until he succeeded in clearing his name
Resigned from the Air Force, joined the Justice League