Just completed Desu Ex Human Revolution again. Game don't like me though... was doing a second try on the Pacifist run, but it refused to give it to me. What I know I never killed anyone, so somehow someone that I knocked out and had to move must have died, even if I was careful not moving bodies unless I had to.
I always like to go stealthy with my tranquilizers but can't resist hacking bots/turrets which always means someone dies in my playthroughs of Deus Ex.