The prone form of the man under the unfortunate focus of the two wizard and their various curses twitches and jerks like a fish in its very last death throes, bruises colouring his arms, face, the expanse of skin beneath his clothing-- until Lucius twitches his wand with more determination and utters a sneered, "Avada Kedavra." A flash of green and then all is still.

It's not really a mercy so much as it is time management.

The sounds of the outdoors fails to make Lucius nervous, quietly confident in the spells cast to keep things outside from getting in, and things from within getting out. He gestures towards the documents. "Is everyone who knows of these dead?"