Killers of the Flower Moon: The Osage Murders and the Birth of the FBI by David Grann:
In one of the courtrooms, I met Marvin Stepson. An Osage man in his seventies with expressive gray eyebrows and a deliberate manner, he served as a chief trial court judge. He was the grandson of William Stepson, the steer-roping champion who had died, of suspected poisoning, in 1922. Authorities never prosecuted anyone for Stepson’s murder, but they came to believe that Kelsie Morrison—the man who had killed Anna Brown—was responsible. By 1922, Morrison had divorced his Osage wife, and after Stepson’s death he married Stepson’s widow, Tillie, making himself the guardian of her two children. One of Morrison’s associates told the bureau that Morrison had admitted to him that he had killed Stepson so that he could marry Tillie and get control of her invaluable estate.
Stepson’s death was usually included in the official tally of murders during the Reign of Terror. But as I sat with Marvin on one of the wooden courtroom benches, he revealed that the targeting of his family did not end with his grandfather. After marrying Morrison, Tillie grew suspicious of him, especially after Morrison was overheard talking about the effects of the poison strychnine. Tillie confided to her lawyer that she wanted to prevent Morrison from inheriting her estate and to rescind her guardianship of her children. But in July 1923, before she had enacted these changes, she, too, died of suspected poisoning. Morrison stole much of her fortune. According to letters that Morrison wrote, he planned to sell a portion of the estate he had swindled to none other than H. G. Burt, the banker who appeared to be involved in the killing of Vaughan. Tillie’s death was never investigated, though Morrison admitted to an associate that he had killed her and asked him why he didn’t get an Indian squaw and do the same. Marvin Stepson, who had spent years researching what had happened to his grandparents, told me, “Kelsie murdered them both, and left my father an orphan.”