http://books.google.com/books?id=B30UAAAAYAAJ&pg=PA175&lpg=PA175&dq=Linn+County+civil+war+history&source=bl&ots=eyzi88AnLW&sig=vngA7z1ox83EUEGtzkm69L_Xk50&hl=en&ei=jEEnSuidC6C-NIWryYQF&sa=X&oi=book_result&ct=result&resnum=4#PPA609,M1
Note the March 16, 1862 date of death. No mention is made of it being anything but a natural death .
John R