White relied upon Agent Burger to guide him through the murk
of the previous federal investigation. Agent Burger had worked on
the case for a year and a half, and during that time he had pursued
many of the same leads as the private eyes hired by Hale and
Mathis and Mollie’s family. By drawing on Agent Burger’s
findings, White was able to quickly rule out many of the suspects,
including Anna’s ex-husband, Oda Brown. His alibi—that he was
with another woman—checked out, and it became clear that the
forger who had implicated Brown had fabricated his story hoping
to bargain with prosecutors for better prison conditions. Further
investigation eliminated other suspects, like the ruffian oil
workers who had been pinpointed by Harve Freas, the ousted
sheriff.
White then explored the rumor that Rose Osage had killed Anna
because Anna had tried to seduce her boyfriend, Joe Allen. (Rose
and Joe had since married.) White learned of the statement that
private investigator No. 28 had obtained from the Kaw Indian
woman, in which Rose had confessed to being the murderer. In a
field report, an agent from the bureau observed, “It is a matter of
common knowledge that Rose...was of a violent and jealous
disposition.” The Fairfax town marshal also shared with agents a
disturbing detail: around the time of Anna’s murder, he had found
a dark stain on the backseat of Rose’s car. It looked like blood, he
said.