Dog Stares at a Ghostly Apparition

(Click Photo to Enlarge)

This strange picture was sent in anonymously via email. The sender writes:

This picture was taken in my townhouse in Aurora, CO. At first I thought is was the camera strap cause I here that it sometimes causes a ghostly effect. But when I looked at it closer, I noticed that you can see through it. Also, it appears that my dog can see it too.