At the start of Jeff's Chapter (the one right after Obi), as soon as you exit the door you should see a pool of blood besides some stairs. In the pool of blood is the hatchet, from there you simply just need to kill the first minion you come to which takes a little bit since you will have to do the acid barrel, up the steps to the audio tape, back down and through the opened door... you may find a minion on the other side already there, if not a little further and you will see one. Hope this helps.