My interview today with Michael Smerconish
Landis told the Columbus Dispatch in 1988 (25th anniversary article) that he found a "fragment" on the seat and handed it over to "somebody." That appears to be the first instance in which he mentioned anything like this. It differs significantly from his current account, in which he says it was an intact bullet and that he left it at the foot of the President's gurney. His credibility is very suspect.
There is the further issue, re memory, which Posner doesn't mention, and that is how PTSD affects memory. In addition to that, there is Robenalt saying he helped Landis "process" his memories for the book. We've got ethical and other issues here.
Posner, on his own Substack, says he essentially thinks Landis is looking for a bigger slice of fame. Maybe that applies in spades to Robenalt?
My take on the book, updated with Gerald's Substack piece, the NYT piece, the Cleveland Plain Dealer piece, Robenalt's Vanity Fair piece, and my personal experience from having lived in the DFW Metroplex for a decade, is here https://socraticgadfly.blogspot.com/2023/09/a-new-jfk-conspiracy-theory-and-book.html