Wallace could have run into some stranger who was passing through and said something to him he later thought might be incriminating like-Have you seen police around? Of course it may not have been Wallace at all.
Yes, there is a theory, posited by another, that it was a crouching Wallace who made like Julia at the door. We don't know for sure how much attention Close was paying or how well he saw "her". Some of Close's testimony seemed to be what he thought but didn't exactly know. If it was Julia and Wallace did it then that was about the last minute of her life.
This my opinion and to the best of my knowledge, that is, if I'm not joking.