Here is a note posted to the Groundspeak forum by Indiana Jeff:

Well, my LOST ARK cache has gone missing...I had it on top of a mountain which required a 3 hour hike up, with no trails, so I can only assume that a park ranger or deranged anti-geocacher has taken it...however, I will replace it at a new location and make it a little harder to get the exact coordinates next time...GEOCACHERS BEWARE! THE GEOCACHER THIEF IS ON THE LOOSE IN THE PHOENIX AREA!