PAWHUSKA — Bestselling author David Grann will be in Pawhuska Saturday signing copies of his new book, “Killers of the Flower Moon: The Osage Murders and the Birth of the FBI.”


Grann is to sign from 10 a.m. to 2 p.m. Saturday at The Water Bird Gallery, 134 E. 6th St., across the street from the post office. Sunday, he also will be signing at the Tall Chief Theater in Fairfax, 30 miles southwest of Pawhuska, from 2-5 p.m.


A longtime staff writer of The New Yorker magazine, Grann made numerous visits to the area while researching the project. “Killers of the Flower Moon” chronicles a series of murders that occurred over the first three decades of the 20th Century — after grazing rights and oil royalties had made the Osage “the richest people per capita in the world.”


Grann called the Osage Reign of Terror “one of the most sinister crimes in American history.”


“This is the rare case where there really is a conspiracy,” the author said. “There were so many different murders, so many different victims, so many different investigations.”


Although the Federal Bureau of Investigation eventually obtained convictions of a few perpetrators, many of the Osage murders were never solved, Grann said.


A film version was recently released of Grann’s previous book, “The Lost City of Z” — about a search for an indigenous culture in the Amazon. Movie rights to his newest release have already sold for a record $5 million.