Chess on an Infinite Plane (hitthepin - Bad_Dobby_Fischer)

I really hate to ask this, but a mod is not allowed to assume anything. Which knight is Black using to capture a pawn?
board after White's move:
10.(6,4)x(5,5)

I pretty much assumed that was your move, but I didn't want to give unintended help.
10.(6,4)x(5,5)...Nx(5,5)
np
8.N(7,5)...G(7,8)