Sure, it is a possibility, but there is also a possibility that someone did see her and just did not realize it was her. I see joggers in my area all the time, that does not mean if they went missing or I saw a picture of them that I would recognize them. Most days, when hubby is on travel, the only person I see at the end of each day is my mom. If I went missing and she cleaned my house while I was gone and she was the last one to see me, does that mean she killed me and cleaned up the evidence? No. It just means she was the last person who actually recognizes me who saw me last. I am sure that there are countless women who have left their husband at home, unnoticed by others, to run an errand, go running...whatever and have been the victim of a random killer. Just not a convincing argument for "he definitely did it".