A manuscript penned by the man who shot and killed Lee Harvey Oswald days after the assassination of President John F. Kennedy is up for auction.

Boston-based RR Auction says the 24-page manuscript set to be auctioned Wednesday was written by Jack Ruby while in prison. It details his actions after Oswald assassinated Kennedy on Nov. 22, 1963, and before Oswald was shot in police custody two days later.

Ruby wrote the manuscript after being convicted of murder. Ruby’s family says it was to be used by Ruby’s defense if he had been granted a new trial to show the killing wasn’t premeditated.

Ruby’s conviction was later overturned. He died while waiting for a new trial.

Also up for auction Wednesday is a medallion worn by Kennedy at Harvard University.

(AP)