Monthly Mystery: The Librarian’s Discovery - Part Three

Benny Bookman, the librarian at the Oddtown Public Library, has stumbled upon a doubly disturbing discovery. Initially, he uncovered a book defaced by borrowers' scribbles. However, the distress deepened when he sensed these weren't mere random markings; rather, someone might be orchestrating a sinister plan, communicating covertly with fellow borrowers. In this three-part mystery, can you assist Benny in deciphering the plan's details and identifying the conspirators, enabling him to report them promptly to the authorities.

Part Three

This is Part Three of a three-part series. You may choose to first solve Part One and Part Two. Otherwise, you may just solve this puzzle. 

Please note: The results from the previous two puzzles may have been shared within the puzzle below.

Clue:

Benny has successfully deciphered the unfolding plan and now seeks the identities of potential suspects before reporting the matter to the authorities. The underlined book, introduced to the library brand new on February 4, 1985, underwent a series of checkouts by 12 individuals from the day it arrived until Benny observed the disturbing scribbles. Crucially, the book had never been available on the library shelves, indicating that 3 out of the 12 borrowers who checked it out might be the masterminds behind the scheme. Delve into the check-out card and deduce which three borrowers could potentially be our culprits.

Please look for clues in Parts One and Two for help with the answer.