These two links (internet archive and archive today respectively) link to a now erased Amazon listing for an e-book titled "The Shooting of Charlie Kirk" published on September 9th.
Check it out:
https://web.archive.org/web/20250911163616/https://www.amazon.com/dp/B0FQMF466K
https://archive.is/VGsXM
No info on the supposed author, nor any other info on the listing itself. I'll come back and update in the comment section if anything else comes to light.
("ASIN" Is basically amazon's in-house version of an ISBN number)