In my deep high school years, this was my Stranger, both eye opening and mind expanding into the realms of nihilism and existentialism. Face of a Hero by Pierre Boulle tells the story of a prosecutor who witnesses an accidental, possibly suicidal drowning which he could have prevented, then tries a man he knows to be innocent of the murder in order to gain esteem and become a local hero.
One of the most unforgettable books I have ever read. It is quite unfortunately out of print but used editions can be found both on Abebooks, Amazon and Alibris. Boulle is better known for his 1952 novel, Bridge on the River Kwai and Planet of the Apes from 1963.
From a man with such a brilliant and creative mind, I hope people seek out this lesser known treasure.