Answer:
Swanson used figurative language in his writing in "Chasing Lincoln's killer"
Because he attempted to describe as best as he could the events he narrates in the book to let the reader know his perspective of things.
Step-by-step explanation:
First of all, Simile is very present in the book an example of this is: "He was dog-tired, and his body ached from hours of riding in horse neck". The reason he uses these elements is that he wants to represent the element he is describing with a popular idea or generalization that people use very often to describe something. Or to be understood from a popular culture point of view. He uses language that he believes is going to make the target audience understand perfectly his Ideas. Even though, they can result in very subjective and require explanations or people not used to employ these concepts.