Answer :
Checking the incentive of the speaker/writer/ is the best way to identify an overly biased historical source.
The best way to identify an overly biased historical source is to investigate the writer's motivation, because bias includes personal opinions about something that is not factual and one-sided points of view that are untrue.
The letter from James Wickersham is extremely biased and an extremely untrustworthy source of information. Many of the people involved on that day were charged with crimes, leaving Wickersham with a lot to lose if he provided accurate information. The contradictory statements made by Wickersham, as well as the consequences he may face if he tells the truth, point to his letter being untrustworthy.
More on bias can be found here-
https://brainly.com/question/24491228
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