When he was a child, John D. Rockefeller watched his father count his money—huge wads of which he refused to keep in a bank and lovingly stacked in front of his impressionable son. “He made a practice of never carrying less than $1,000,” the oil baron recalled later in life, “and he kept it in his pocket. He was able to take care of himself, and was not afraid to carry his money.”

William Avery Rockefeller’s son would go on to become one of the richest men of all time. Famously money-hungry, John D. spoke admiringly of his father’s piles of cash long after he had made a fortune that would have surpassed his father’s wildest dreams. But though the head of Standard Oil was proud to tell the world where he had gotten his own appreciation for cold hard cash, he always excluded a detail: where his father’s cash came from.

In fact, William’s money had come from a slew of shady business ventures, from pretending to be a deaf and blind peddler to posing as a doctor to hawk patent medicines. But after his stratospheric rise to the heights of Gilded Age business, John D. Rockefeller did everything he could to downplay the exploits of his parent. He was in his sixties before accusations about his father’s unethical business practices and possible criminal behavior came back to haunt him—accusations that sparked a race to find out the truth about Rockefeller’s father.

The accusations came courtesy of Ida Tarbell, the muckraking journalist who exposed Standard Oil’s secretive business practices, which included cutting secret deals to squelch its competitors. As the capstone to her multi-part exposé in McClure’s magazine, she published a two-part character study of John D. Rockefeller in 1905.

The articles painted a portrait of a man obsessed with money—an intimidating, secretive figure whose personality was warped by ambition. But just as shocking as her portrait of one of the United States’ most famous men was what she wrote about his father. Tarbell accused William Avery Rockefeller of posing as a physician and exploiting others for financial gain, and brought to light allegations of rape and horse thievery against him.

During John D.’s childhood, she wrote, his father had been “the leader in all that was reckless and wild in the community, and was classed by the respectable and steady-going as a dangerous character on whom no doubt much was fastened that did not belong.” William had gone missing for long periods of time during John D.’s childhood, she wrote, leaving his family impoverished and forcing them to move from town to town.

John D. had spent a lifetime trying to bury the truth about a relative whose actions threatened the entire empire he had worked so hard to build. Though he publicly claimed he had built his career on the lessons of his parents, he had really only modeled himself after one, his strict mother Eliza. She had long since been abandoned by William Avery Rockefeller, the renegade husband she had been unable to reform.

Suspected of horse stealing and even indicted for rape in 1849, William had been an unstable father figure. But search as Tarbell might for the man nicknamed “Devil Bill,” she had not been able to track him beyond John D.’s young adulthood.

The oil magnate was incensed by what he saw as a maligning of his father. Though he typically refused to let down his guard, one journalist who showed him Tarbell’s story witnessed a rare crack in his famous veneer. “The poison tongue of this poison woman,” he ranted. “What a wretched utterance from one calling herself a historian.”

READ MORE: 10 Things You May Not Know About John D. Rockefeller

Now the world knew the truth about William Rockefeller—but nobody knew where he was. His whereabouts were only exposed thanks to another news legend who despised Rockefeller and his business practices. Joseph Pulitzer, the news magnate who owned the World, sensed that exposing Rockefeller’s roots would not just humiliate the man, but sell more papers. Beginning in 1901, he offered an $8,000 reward—the equivalent of over $240,000 in modern dollars—for anyone who could reveal the whereabouts of Rockefeller’s mysterious father.

Pulitzer sent star reporters across the country to try to track down William, but they came back empty-handed. Seven years later, in 1908, a World reporter named A.B. Macdonald finally got the scoop. But he was too late: William Rockefeller had died six months earlier.

That didn’t stop him from fleshing out the story of William Rockefeller in print. The article had even more bombshells about the magnates’ father: For years, he had lived under assumed names and was known as Dr. Levingston before his death. He “had a big jug of medicine and [he] treated all diseases from the same jug,” an associate recalled, remembering that the supposed doctor would laugh about his concoction magically being able to cure anyone willing to give him money.

The article also claimed that William Rockefeller had been a bigamist. During John D. Rockefeller’s childhood, he had lived with John D.’s mother, Eliza, but a mistress had lived under the same roof as a housekeeper. Eventually, he had remarried without obtaining a divorce, living a double life and splitting his time between two families. His new wife, Margaret Allen, ended up staying married to him for 50 years and did not realize he had not legally married her until after his death.

The accusations of quackery, rape and bigamy all flew in the face of the thrifty, wholesome image John D. Rockefeller had carefully crafted for years. They also represented serious moral outrages during a conservative era. But perhaps the most shocking accusation of all was that his sons had known his whereabouts for 25 years, and had been quietly supporting him.

This claim was vigorously denied by Frank Rockefeller, who called the story an “unqualified lie” in a statement. He stated that his father had been forced into seclusion “precisely to protect himself from being hounded by cranks and others who would break in upon the peace and quiet of his retired life.”

The story was true, however. The Rockefellers had known their father’s location for years and had been sending him money, perhaps in an effort to buy his silence. As for John D. Rockefeller, he ignored Pulitzer’s exposé and tried to move on—presumably eager for the public to forget his connection to—and similarities with—a father who had no qualms about cheating others in the name of profit. He had spent a lifetime trying to escape his roots, and wasn’t about to stop now.