It's impossible to kill him. It's too dangerous to keep him alive.

Traitor's Heart

Five years ago, Nick Brody lost his memory. He has moved on with his life when two strangers offer him a link to the unknown - his secret military past. After providing Nick with a mysterious picture and a cryptic message, the strangers turn up dead. The deeper he digs, the more Nick realizes that his puzzling past won't just haunt him, it could kill him.