Was he instructed to put himself in about the worst possible place for the official story of Mr Oswald's descent----------standing near the stairs on the fifth floor?
I assume that Truly simply told him to leave the spent shells by the window and hide the rifle beneath boxes of books at the top of the stairs....and he assumed that Dougherty remain out of sight ..... pretending to be filling book orders. Marrion Baker inadvertently made a mess of it all by barging into the building ......