An interesting piece, kindly brought to my attention by Zander Sturgill, on the distinct authors of the Book of Mormon:
http://ldsmag.com/insights-into-the-authenticity-of-the-book-of-mormon/
Several others have approached the topic of potentially multiple authorship from different perspectives. Here are two relevant books:
Roger R. Keller, Book of Mormon Authors: Their Words and Messages
Grant Hardy, Understanding the Book of Mormon
And then there’s the whole matter of computerized “word print studies.”