King Richard III's image in Shakespeare's work

If it can be convincingly argued that King Richard III'was not as evil or tyrannical as William Shakespeare portrayed in his famous work,'then the inescapable questions are': (i) what were the historical sources or accounts Shakespeare used to write his script '? '(ii) 'Did Shakespeare distort the sources to make the English monarch a wicked character ? If Shakespeare distorted the sources,'the pertinent question is: why ? But, 'it isn''t clear if Shakespeare had ever claimed to be an historian, or that his writing on King Richard III was a strictly historical account.