No, Mammoth Lakes was not in the original search area, it was just outside it.
The actual area where the items were found is called Reds Meadow which is west of Mammoth Lakes and in a pretty remote area.
This thread has several pics of the area.
http://www.freerepublic.com/focus/f-news/2095342/posts
Meant to ping you to above post also.
I have been there many many times. There is a pack station and a little store/restaurant there. There are lots of trails into the wilderness areas around there. My question is how he got down there was that even on his flight plan.