YES that definitely happened. She would have left the files in a separate place (probably the bakery or something) and instructions for him to find them if she left. As for her stuff, she's got her scoped rifle in there with a decent supply of ammunition for it, and Kyle would have already gotten both of her Olympic medals and an assortment of pictures, though Olivia probably would have never mentioned having those two things to Costigan. So when he comes by it'll just be her rifle sort of hidden away, and the place will look undisturbed because Kyle is good like that. She didn't have a lot of stuff and most of it was useful and would have been on her person anyway haha.