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.