There are several references to men named “William Thompson” in the records of early California, but it is virtually impossible to determine how many William Thompsons there actually were and which one was the Donner Party rescuer. It seems likely that he was the William Thompson who worked at Nathan Spear’s mill in San Francisco in 1845-46.
During the Third Relief Thompson rescued Frances Donner, for which he was paid $50.00. Since he served in the Donner relief effort for 59 days altogether at $3.00 per day, his earnings totaled $227.00.
Thompson may also have been the William Thompson who married Lucinda Jane Saunders at Sutter’s Fort on 14 April 1847. (It is tempting to identify his bride as the notorious Lucinda who so annoyed Heinrich Lienhard — see his From St. Louis to Sutter’s Fort, Norman: University of Oklahoma Press, 1961.)
Bancroft reports that a William Thompson, who was killed by a bull in Honolulu in 1850 and had been a resident of California for the previous seven years, may or may not have been the Donner Party rescuer.
New Light on the Donner Party, Kristin Johnson
Ordeal By Hunger, George Stewart