The account came from a usually trusted sports betting expert, R.J. Bell, who is an odds-provider for the Associated Press. A mysterious gambler with uncanny luck had bet on the winning team in all of the first five games in the series, Bell wrote on Twitter Tuesday. By “letting it ride” — that is, reinvesting his winnings — on each game, the unidentified bettor had raked in a staggering $8 million, Bell claimed. Now, he said, the risk-taker was going all-in on the Dodgers for Game 6.

“CONFIRMED RUMOR,” Bell tweeted. “Unknown Vegas bettor 5-0 in W Series — letting it all ride each game. He bet it all on #Dodgers tonight!!”

Hours later, when the Dodgers beat the Astros 3-1, Bell returned with more news.

“Let It Ride bettor wins again. 6 for 6 in WS! Expected to have $14 Million in action tomorrow!! I’ll let you know who he’s betting ASAP.”

Bell’s tweets stoked a fevered debate on social media and in the comments sections of numerous sports and gambling websites. Some took to calling the unknown bettor the “mystery gambler.”

On Twitter, many users said the story seemed too far-fetched to be true, even by the larger-than-life standards of Vegas. But Bell, the founder of the sports betting site Pregame, is a reliable authority on such matters, so he had plenty of believers.

Details about the man’s identity were scant. Bell said he had spoken to “sources” who told him that the bettor was, indeed, a man, and that he was Eastern European and younger than 30. One source purportedly said he was a frontman for a “mysterious group.” His gambling history in Las Vegas was minimal, but he had placed a few “MONSTER” wagers on Ultimate Fighting Championship matches and was “undefeated on those bets,” according to Bell.

This time around, the gambler had been spreading bets across town, Bell said, rather than attempting to lodge one huge bet in a single establishment. One casino, having heard that the mystery gambler was going to bet on the Dodgers in Game 7, had even changed its odds at the mere sight of him, Bell claimed, tweeting a picture of the supposed changes.

The casino denied the allegation, telling the gambling news network VSiN that an influx of large bets had caused a “temporary money line anomaly.”

VSiN also reported that there didn’t appear to be any $8 million bet on Game 6. Citing anonymous sources, the site reported that “this particular bettor” had only bet a total of about $3 million on the game at a half-dozen different casinos. A sports book director told the site anonymously that reports of a much higher bet were “fake news.” Others were similarly skeptical.

But by that point, speculation was already running wild.

Sports Illustrated’s Daniel Rapaport dubbed the gambler “Sir Let It Ride,” writing, “You know you’re a baller when you single-handedly flip the Vegas lines JUST BY WALKING IN THE BUILDING.”

On Twitter, Bell’s roughly 148,000 followers pondered the man’s origins. Some argued his large bets suggested he was part of a gambling syndicate. Others said he was just an ordinary guy with dumb luck. A few went even farther. “I think he has a time traveling DeLorean,” one user wrote.

Ahead of Game 7, questions simmered over whether he’d place a $14 million bet on the Dodgers. Bell kept things interesting with a string of updates during the afternoon Wednesday, including a curiosity-piquing interview with Fox Sports Radio.

Hazy as the details were, Bell assured listeners, the story was “100 percent” true. He claimed to have spoken with multiple trusted sources who had met with the man and recounted the same things. “It’s impossible that this isn’t true,” Bell said.

According to Bell, sports books up and down the Strip had come to know the man because he had bet successfully on every game so far. “All the books talk among themselves,” he said. “The minute the guy bets at one place they’re calling all their buddies, saying, ‘Hey, he’s on so-and-so.’”

Bell told Fox Sports Radio he had heard the gambler started with a roughly $500,000 bet. By the time the man hit big, he said, he started spreading his bets around, “trying to get $50,000 here, $500,000 there, a million there, and adding it up.”

Rumor had it, Bell said, that “this guy had no idea about betting” and at one point had asked for a receipt for his bet. Maybe that meant he was flying solo. But with all that cash, Bell added, it would make sense that he was a “beard” for a larger gambling group.

“Here’s the paradox,” Bell explained. “Groups care about every penny, meaning if you’re laying 110 or 150, that difference is night and day. The fact that they seem indifferent to what they’re laying belies the idea, goes against the idea, that it’s a group.”

“So on one hand you’d think maybe it’s some dumb rich kid,” he said. “But on the other hand, if it’s a syndicate they would care about every penny, and they don’t seem to. I’ve never seen a story like this.”

The buzz continued until just before game time. Then, in a tweet close to 7 p.m., Bell announced a new development: There would be no Game 7 bet. The mystery gambler was bowing out with $14 million.

“Sir Let It Ride is no more. Long live Sir Let It Ride,” wrote Rapaport, of Sports Illustrated.

Incredulity about Bell’s dispatches seemed to grow in the denouement. “Bell has not provided evidence,” Casinopedia author Kathryn Allison wrote, “but his stance appears more to be about stating that no evidence has been provided to disprove it.”

Brent Musburger, a veteran sportscaster who hosts a broadcast show at VSiN, called Bell a “bulls‑‑‑ter” in a tweet Thursday, prompting several bitter responses from Bell. Other Twitter users accused him of concocting the story to gain followers or new users for his sports betting site. “Never any proof,” wrote one.

ESPN gambling writer David Payne Purdum, however, said Bell was onto something. “My reporting produced different details than RJ,” he tweeted Thursday night, “but the crux of the story is true: amazing run by the guy.”

Bell stood by his account. In a statement posted to Twitter on Thursday, he gave a point-by-point recap of his reporting, saying that many “novice eyeballs” had created a “recipe for misunderstanding.”

“I understand that these new viewers/followers don’t know me — don’t know yet how much effort I put into being different than the typical Vegas guy,” he wrote. “Veteran followers know that I don’t float rumors for attention.”

For now, the mystery gambler, if there is one, remains a mystery. Bell said that if any evidence turns up that contradicts his story, he’ll report that, too.

“Nineteen years in Vegas and I can tell you this for sure,” he wrote, “it’s a dangerous place for the uninformed.”