Wow. 
Will, not only must it have been a very difficult means to find out about the loss of a friend, but it is very strange for me to hear about it here.  My heart goes out to you. 
Being a regular "rainier rat" I tend to follow the stories of those that run into problems on Rainier, and I remember well, that of your friend.  That is why when I heard they found the remains of a snowboarder last summer one day when we were up skiing the Nisqually Chutes I remember saying to a friend at the time, "that has to be that young doctor from Georgia".  Sure enough the park service later confirmed it and notified his family.  As I recall he was discovered in the Pebble Creek drainage at about the 6700 ft level.  There's some cliffs in there; he might have gon off and been hurt in the fall; possibly buried in a slide.  Mike Gauthier probably knows more. 
A quick search yeilded this excerpt of the article: 
Rainier remains may be young doctor's  
The News Tribune; Tacoma, Wash.; Jul 19, 2001; Skip Card;  
Words in Document: 245 
Available Formats: 
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Abstract: 
Mount Rainier rangers Wednesday recovered what appear to be the remains of William "Tres" [Tres Teitjen], a medical school graduate who disappeared in 1999 while snowboarding down the Muir Snowfield. 
Teitjen, 28, moved from Georgia to Seattle in June 1999 to begin a residency program at Harborview Medical Center. Although active in the outdoors, he never before had been to Mount Rainier ... 
  
Sorry man...