What was the occupation of the man known as Papillon?

My God! He sounds like the Count of Monte Cristi! Unjustly imprisoned but had the will to effectively escape! Good for him!

Player #39280873, Steve McQueen RIP Played Papillon in 1973 film.He was stunning.The story was all the more moving as it was true

I read that he was convicted of killing a pimp? Boy, those French people love their pimps!