Article on Fox at http://www.foxnews.com/story/0,2933,154880,00.html includes her diamond in the things she left behind. I don't know about anyone else, but I NEVER left my diamond anywhere. It was always with me. This alone makes her disappearance seem very suspicious to me.
"Mason, who had just returned from a run himself, said Wilbanks prefers to run by herself, but “she doesn’t just go and run and hide."
That must explain the excessive sweat build-up and the sweaty shoes and clothes he had on him when the detectives arrived. I wonder if they asked him for his jogging clothes?