Across the plains of Osage, Oklahoma, small flowers begin to bloom in April. By May, however, larger plants spring up, overshadow, and choke out the smaller flowers that had blossomed first. The Osage Indians refer to May as the season of “the flower-killing moon.” This natural cycle is a fitting metaphor for the systematic murder of Osage Indians at the hands of greedy settlers wanting claim to Osage lands.

The Osage people occupied a territory that spanned hundreds of millions of acres of the Great Plains, but that changed beginning with Thomas Jefferson’s administration. He referred to Osage nation as his “children,” and that as two peoples that had no memory of any land other than the one they co-inhabited, he hoped for nothing but amiable friendship. But the velvet glove of bonhomie masked an iron fist. The Osage gradually surrendered their ancient lands and burial grounds to make way for an incoming wave of white settlers, who carried the conviction that their intrepid, pioneering spirit entitled them to the choicest lands.

After a century of forced migrations, the Osage eventually occupied a small 50 by 125 square mile plot in southeastern Kansas. They were forced to uproot once again as more pioneers began to move West. They were settled on a small reservation about the size of Delaware, selected because the soil was rocky and appeared devoid of any agricultural merit. What the government did not realize at the time was that the Osage had settled in a section of Oklahoma (from the Choctaw word for “red skin”) that was rich in oil.

The Indians who negotiated the terms of resettlement in Washington, D.C., were able to procure what seemed a peculiar clause in the final document, namely, that any minerals, oil, or other natural resources discovered underground belonged exclusively to the Osage.

It was in this manner that the Osage became fabulously rich, as they leased some of their land to oil tycoons and received a portion of whatever oil was brought to the surface. They received quarterly checks, mere pittances initially, but, eventually, amounts in the hundreds and thousands. The Osage oil fortune was estimated to be the modern equivalent of almost half a billion dollars.

The Osage Indians were given headrights to a resource that the government could not pilfer and that non-Osage could access except through inheritance.  And so the Osage resided there, garnering checks and living like royalty: Model Ts, gaudy chandeliers, diamond jewelry, mansions, and the latest in French fashion.

Mollie Burkhart was a full Osage Indian. She was just a child when her family was forced to migrate from Kansas to Oklahoma. She had married a white man, Ernest Burkhart. Underneath his rough exterior was a gentleness that Mollie picked up on early in their acquaintance, and a romance blossomed between them. She knew some English from the private Catholic school she’d attended as a child, and Ernest studied the Osage language in order to communicate with her in her mother tongue. So they met in the middle, and the marriage seemed to work. After four years of marriage, they had two small children.

In May of 1921, Mollie Burkhart received news that her sister, Anna Brown, was dead. She had left Mollie’s home drunk with Ernest’s brother, Bryan. After she did not return for several days, Mollie grew concerned.  A week later, a young boy discovered Anna’s body rotting in a ravine. The autopsy revealed a bullet hole near the scalp line, though no bullet was recovered. At the funeral, many expressed condolences, including Ernest and Bryan Burkhart’s uncle, William K. Hale. Hale was a pallbearer at Anna’s funeral, and expressed to Mollie his anger over the murder and desire to do all he could to further the investigation. Hale had started as a no-name cattlehand decades earlier, but had become a wealthy and influential member of the county’s elite. Some called him the King of Osage County; Buffalo Bill once called William Hale “a high-class gentlemen.” A pledge from Hale carried weight and Mollie thanked him for his willingness to help with the investigation.

Two months after Anna’s murder, Mollie’s mother, Lizzie, died as well. The family’s doctors (a pair of brothers) were unable to pinpoint the exact nature of the sickness. Anna was one of Mollie’s three sisters. Her sister Minnie had died a few years before from what was called a “wasting sickness,” a nondescript diagnosis to match her nondescript symptoms. Her remaining living sister, Rita, lived nearby with her husband, Bill Smith. Bill had a growing suspicion that these attacks were coordinated, and began to do some of his own digging.

This was not out of the ordinary in those days, where private eyes, sleuths, and judge-appointed citizen posses typically conducted investigations. There existed a lingering suspicion of state (and especially federal) police, so the onus would fall to private citizens.

It became increasingly clear that there was an underlying structure to these attacks, and those who wanted to probe further jeopardized their own lives.

Mollie’s sister and brother-in-law, Rita and Bill Smith, were casualties of this. The couple could hear people sneaking around the perimeter of their home at night, and one night, someone even stole their car. They decided to move closer to town, and hoped that the change of location and their neighbors’ watchdogs would deter further intrusions. But then, one by one, the dogs started to die. Someone was poisoning them. Not long after, Bill, Rita, and their servant were blown up in an explosion that destroyed their entire home. Rita died immediately; Bill followed a few days later. Whatever progress Bill Smith had made on the case had gotten someone’s attention and it cost his and Rita’s lives.

One Osage remarked that, while there were some good, honest white people who cared for his people, many others were looking for opportunities to get closer to the Osage oil wealth. One older white oilman who had taken Osage interests seriously and had the Osage’s trust was Barney McBride. They called upon him to go to D.C., and request a federal investigation. Before McBride could meet with officials about the matter, he was kidnapped outside a billiard hall. His body was discovered in a canal in Maryland. He’d been stripped of everything except his socks and shoes, stabbed multiple times, and his face was brutalized beyond recognition. It was more than a murder—it was a message. The Washington Post called it the most brutal murder in the district. McBride’s murder brought to the public’s attention the conspiratorial nature of the string of Osage deaths.

Another well-meaning Osage ally was W.W. Vaughan, an attorney in the neighboring county and a friend of George Bigheart, a relative of James Bigheart, the Indian who had helped negotiate the terms of Osage resettlement and headship rights decades earlier. George Bigheart was in the hospital and believed that he had been poisoned. Vaughan met with him and spoke with him for several hours before Bigheart stopped breathing. Vaughan immediately called the new sheriff in Osage County (the old sheriff who’d handled Anna’s investigation had been jailed for not enforcing the law). Vaughan told the sheriff that he knew who Bigheart’s killer was. Vaughan’s body was discovered near the train tracks, neck broken and naked except for his socks and shoes, just like McBride in Maryland. The physical evidence he received from Bigheart was no longer on his person.

What the Osage had long suspected was becoming increasingly plain: the Osage were being targeted, and their allies were being eliminated when they lifted so much as a finger to help. The Osage began to turn on their lights at night for fear that they might be next. The locals began to call these deterring lights “‘fraid lights.” Osage and white alike knew that the Osage had every reason to take precautions.

For four years, the murder cases had gone cold. Local police hadn’t turned up anything, and neither had the sleuths that Hale and others had hired. The cases had been dropped. The Osage drafted a resolution pleading for the federal government’s involvement in the case. Word reached the Bureau of Investigation, an obscure branch of the Justice Department that would eventually be restyled the Federal Bureau of Investigation.

In the early 1900s, the BI was not the powerful, well-known entity with which we are familiar today. It was conceived quietly under Theodore Roosevelt’s direction in 1908 without congressional approval because of the lingering mistrust of a national police force. One politician referred to the new branch as a “bureaucratic bastard.” In the bureau’s early days, agents could not carry firearms and could not make arrests.

Edgar J. Hoover was called upon to head this fledgling organization, a position he would hold for the next five decades. He was only 29 when he was assigned to the post. Hoover asked special agent Tom White to move from Houston to Oklahoma City and head up an investigation.

Within a half a year, White had assembled a team with convincing, inconspicuous covers throughout the county, and had garnered leads that previous investigators had missed—or chosen to overlook. He’d managed to separate most of the false leads from the genuine ones.

His team was a group of former Texas Rangers and gunslingers who could pass as townspeople in Osage County. They did not fit the white-collar, college graduate vibe that hard-nosed Hoover insisted his agents conform to, but convincing covers required shirking the D.C. dress code.

One significant discovery that Tom White made was the rampant abuse of the guardianship structure that the federal government had developed for the stewardship of Osage wealth. It was determined that the Osage Indians would be unable to steward their wealth wisely, and so the government assigned guardians to manage individual assets for “half-bloods,” but especially full-blooded Indians. These positions were lucrative because they allowed guardians to dip into the wealth that they were supposed to be preserving for the sake of their Indian wards. Every item the Indian wards wanted to purchase had to go through the guardian. Those guardians who also owned stores would sell those goods to Indians at inflated prices. They would entrust the headright funds to particular banks in exchange for compensation. They would buy homes and cars in the ward’s name that the ward never desired or knew about. Even less discreetly, some would simply steal from their accounts.

Lawmen, attorneys, and judges were in bed with many of these guardians. Judges covered up transactions in exchange for votes. Attorneys would find loopholes and bar any instances of abuse from being brought before a court. In the event of murder, which happened most frequently to Indians with guardians, doctors would attribute symptoms to nondescript illnesses like “consumption” or “wasting sickness” when they’d actually been poisoned. They would hide evidence at crime scenes. The Osage were not blind to such schemes but were powerless to stop them. The plots to murder these Indians for their wealth were chillingly calculated, and the low-hanging fruit of guardianship posts went to the judges’ close friends and associates.

As White learned more about the headright structure, the probable motivations in the murders in Mollie Burkhart’s family became painfully apparent. Far from a string of senseless murders, the order of death was wickedly strategic. Anna Brown was divorced, so her headright money went to her family. When the mother, Lizzie, died, her headright money went to the two remaining sisters, Mollie Burkhart and Rita Smith. Rita and Bill Smith were killed next. Whoever arranged for the killing apparently had a working knowledge of the couple’s will, which stipulated that, should they die simultaneously, the headright would not pass to the non-Osage husband (Bill), but to remaining Osage family members on Rita’s side. With Rita and Bill dead, the only remaining Osage family member was Mollie. Because headrights belonged exclusively to the tribe, no non-Osage had access to it—except through marriage. But Mollie was married to Ernest Burkhart, who stood to become the sole recipient of Mollie’s entire family’s birthright if she died—and it seemed her diabetes was getting the better of her. Mollie eventually grew suspicious about the “insulin” shots that the doctors were administering when her health continued to deteriorate despite the doctors’ interventions. She got word to her priest that she was being slowly poisoned, and this message was eventually relayed to investigator Tom White.

Witness accounts confirmed White’s theory about William Hale and his nephews’ involvement in murdering for headrights. One witness was a man named Pike, the sleuth Hale had hired in 1921. Pike told White that he’d been instructed not to expose but to obscure the circumstances of Anna Brown’s murder—through planting evidence, fabricating plausible alibis for the guilty, and misdirecting the investigation. This was all to cover for Bryan, who had been present for and participated in Anna’s murder. Pike also revealed that in addition to Hale and Bryan, Mollie’s own husband, Ernest, had been present at these private meetings.

Hale was the spider at the center of these intricate webs, forming a devious and heinous long-con that involved not only high-ranking politicians, attorneys, doctors, and law enforcement, but Molly Burkhart’s closest friends and family members.

White had gathered sufficient evidence and witness accounts to link William Hale and Ernest and Bryan Burkhart to the murders of Anna Brown, Rita and Bill Smith, and another Osage named Henry Roan, whom Hale had killed after manipulating Roan into making Hale the beneficiary of his life insurance policy.

When Tom White and his team questioned Ernest Burkhart, he began to crack. He denied his involvement until Blackie Thompson, a legendary outlaw, was brought in and swore that Ernest Burkhart had been present when Hale asked Thompson to bomb Bill and Rita Smith’s home. Burkhart seemed torn between a desire to unburden his conscience and a deep fear of his uncle.

Ernest eventually agreed to testify for the prosecution against Hale. White and Hoover fought to have Hale tried in federal court for fear that he would find ways to tamper with court proceedings if the trial proceeded in Oklahoma. It was, however, determined that it was a state case, and as predicted, Hale did everything in his considerable power to thwart justice. He lied, bribed, and threatened jury members, found ways to relay messages to witnesses, offering them wealth and even freedom from prison if they recanted their testimonies. While on the stand, Hale told the court that the investigators had attempted to coerce a confession through beatings and electroshock.

Hale’s team of attorneys had managed to get the witnesses to go back on their signed statements and say that they were signed under duress. Ernest Burkhart had been swayed (or intimidated) into testifying for the defense instead of the prosecution.

Eventually, however, Ernest Burkhart’s conscience prevailed and he withdrew his not-guilty plea. He said he was ready to tell the truth and that Hale’s lawyers had fed him the narrative that investigators had forced a confession at gunpoint.

Hale was cool and confident until the moment when the jury returned a guilty verdict. He was sentenced to lifetime in prison.

The tragedy of Mollie’s family was one of numerous cases, many of which went unpunished. There were at least 24 deaths linked to the plot that Hale had coordinated, but it is believed that there were hundreds of other such cases swept under the rug. One expert on the Osage people claimed that if Hale had given a full confession, the majority of Osage county’s prominent townspeople would have been incarcerated.

There were other incidents, like the case of an Osage woman named Mary Elkins. She married a mediocre boxer who locked her in the house, beat her and got her addicted to opioids to expedite her death. Thankfully the police rescued her, but those involved in the plot were never charged, even when incriminating evidence was discovered.

Over a 16-year period, from 1907 to 1923, there was an average of 38 deaths per year among the Osage, which was far above the average death rate, especially for a people as wealthy as the Osage. In 2011, after a lawsuit that lasted over a decade, the United States government agreed to a settlement in the amount of $380 million to compensate for at least some of the funds that were lost through guardian abuse.

Today, the tribe’s population is 20,000—4,000 of whom still reside in Osage County, Oklahoma. It’s quieter in the town. Oil doesn’t fetch as much money, especially with the legal fees on drilling enacted in 2014. The oil tycoons and wealthy businessmen no longer flock to the town as they did a century ago.

The Osage murder cases helped build the Bureau of Investigation’s credibility, and it was even turned into a movie featuring James Stewart in the late 1950s. Today, it is a little-known case, a forgotten chapter of American history.  The general public has largely forgotten, but among the Osage, the memory runs deep and remains painful.