Dishonored: Non lethal solution for Torturer?

[Snatcher]

I did a non-lethal playtrough and I didn't need to kill te torturer.

 

[Tallim]

Guards killed him for me...... although I have no idea why. They were fighting in the hallway, his dog was still in the room but that was it.

 

[Kepe]

I strangled the torturer, and at the end of the level in the stat screen it said "defeated the torturer" so the game does aknowledge the non-lethal way too.