Responses
I think he would probably investigating, as actually Undertaker is a renegade that is going against the reaper order of things. They probably must want to take him down too.
I can't assure it as Knox could be a double agent of some sort, but it just make sense that the Reapers are trying to found Undertaker
Is the reaper by the name Knox, in cahoots with the Undertaker? I wouldn't see any other reason why he'd work in a facility meant to serve Zombie!Ciel.