“He came in very hungry,” says Percal, one of his early mentors. “Amazing in his focus and hard work. He wanted to make it.” After years of hustle, Tomlinson began hauling in seven-figure commissions. “If you are on your game and know your shit, it is easy as hell and fun as fuck,” he says.

Like most luxury brokers in Miami, Tomlinson crossed paths with the Jills. “I never had a taste for Jill Eber,” he says, having once chastised her for contacting one of his clients. But he and Jill Hertzberg had what he calls a “flirty relationship.” On January 1, 2015, Tomlinson texted Hertzberg about viewing a property she had listed for $4.5 million.

“What is best for you handsome?” she replied. “I don’t want you to wait one second, My Lord.”

“Oh ur adorbs,” he responded. “I adore working w u. A pro! U deserve all ur success. And . . . spend that money! Can’t take it w you.”

By that point, however, Tomlinson had already begun to suspect that the Jills were rigging the real-estate database. The day before, on New Year’s Eve, he had been contacted by another superstar agent at Coldwell Banker. The firm’s Miami office was a hotbed of competition where 150 agents, including the Jills and their 10-person staff, squared off in a blood sport for buyers and sellers. “Kevin, you’re the tech guy,” the agent told Tomlinson, handing him a pink Post-It note with the address of a $2.3 million home in an exclusive golf-course community. “I know the Jills had this listing for over four years, but we can’t find it anywhere on the M.L.S. Can you help me?”

“I don’t go out on New Year’s,” says Tomlinson, a teetotaler. So he took the suspect address home to his penthouse condo, lit candles, poured himself an iced tea, and sat down at his computer. The night stretched on. He heard the fireworks explode and watched the sun rise into 2015. But the biggest firecracker was on his computer screen: the $2.3 million listing seemed to have vanished from the M.L.S. “I was trying all these ways of searching for the property, but it wouldn’t come up,” he says. “I ended up searching via the Jills’ license number.”

By the time the new year had dawned, Tomlinson had figured out what the Jills were up to. Someone had put spaces in the address of the listing, and moved it to “the ghetto.” The data manipulations had made the house disappear from the M.L.S. for 1,228 days. The Jills didn’t have to worry about anyone poaching the listing, because there was no way to find it. “It gave them an unfair advantage,” Tomlinson says.

Suddenly, Kevin from Cleveland had a new mission. “Once he discovered this impropriety, he became obsessed with finding out all the different instances of it,” says his friend and fellow broker Beth Butler. Tomlinson investigated for four months. Homes, he knew, are like fruit: they’re most attractive when fresh. The industry term is “shopworn.” It’s “when your property has been seen by so many realtors and so many people that nobody else wants to see it,” testified Robert Sadler, the chief compliance officer for the Miami Association of Realtors. As Tomlinson dug deeper, he discovered that the Jills—or someone in their office—had made 552 data manipulations on 51 of their listings to erase a cumulative 23,740 days that the properties had gone unsold. The move allowed the Jills to “keep control of their expired listings,” Tomlinson later wrote, and earn “an extra $3 million in commissions.”

The hidden days also meant that some unsuspecting buyers may have purchased houses based on manipulated data. During the time the Jills were altering the listings, their clients included J. Paul Getty’s granddaughter Christina, Obama official Fred Hochberg, and fashion kingpin Tommy Hilfiger. Hilfiger’s house at 605 Ocean Boulevard on Golden Beach is a seven-bedroom, 14,075-square-foot mansion. After it failed to sell at its initial listing price of $18.5 million, eight data manipulations made the house disappear from the M.L.S. for 375 days. The Jills then re-listed it for $21 million, before selling it to Hilfiger and his wife for $17.25 million. The altered data, says an agent familiar with the sale, made it look like Hilfiger was getting a 20 percent discount.