Oh my head hurts!!! Here was something I was thinking about: what if the body was buried so deeply that they didn't see anything, and the recent rains (heavy rains at that) exposed the earth?
Then again, it could have been that whoever was watching all of this before 9/11 decided to place the body there AFTER it had been searched.
But to have only found skeletal remains, it must have been buried SOMEWHERE for a long time.
No, if exposed the body would have skeletonized very rapidly in the DC summer heat and humidity.