As the others have mentioned, thanks for your inside knowledge about the park. I am thinking, could you post some information, or open some threads regarding Diana on any hiking or out door forums that you are a member of. Some oft he more dedicated hikers who have since returned home might have noticed her alone, or maybe hiking with a new "friend" or "friends" (espescially if she ventured into the Canyon proper where there are fewer hikers and people stand out more). Diana did not have true hiking gear and is clean cut. Thus, she should stand out if she joined either a small group of dedicated hikers (and was befriended by somebody in the group, or if she was approached by "Desert rats" (term used to describe often drugged out squatters, drifters, and recluses in southren Califronia deserts. I don't know if the Grand Canyon has a lot of these types, but some of the deserts in socal sure did. Some were dangerous, most were just drugged, or plain weird.)