Had the security guard at the entrance to the Rivers Casino Philadelphia bothered to check, the man could have produced a driver’s license that identified him as 31 years old, even though the photo ID bore little resemblance.

But the 20-year-old man skated by the preoccupied security guard without being carded on Sept. 19, 2020, according to surveillance video. Two minutes later, he entered the high-limit room, where the Fishtown casino says it offers “high-stakes gaming and first-class service.”

The young man bought $1,650 in chips from a blackjack dealer and played at that table, and another table, for nearly an hour without being carded. No alcohol was consumed.

Then his girlfriend tipped off the casino.

Casino security and the Pennsylvania State Police confronted the gambler, and he confessed to being under the legal 21 age for gaming in Pennsylvania.

» READ MORE: Three underage gamblers sneaked into the Rivers Casino Philadelphia. It cost the casino $62,500 in fines

The underage gambler was not identified in the consent agreement approved Wednesday by the Pennsylvania Gaming Control Board. The agreement did not indicate whether he won or lost money. But, in the end, both he and the casino were losers.

The man was given a citation for underage gaming and permanently evicted from the casino. Rivers Casino agreed to pay a $10,000 fine plus a $2,500 administrative fee. It was the fourth time since 2016 that the casino, formerly known as SugarHouse, has been penalized for allowing underage gaming. Its track record may be the source of further inquiry at a scheduled April 26 hearing in Philadelphia on the casino’s license renewal.

On Wednesday, members of the gaming control board were mostly curious about the girlfriend.

“But for this girlfriend turning him in, would he have ever been discovered to be underage?” asked the gaming board’s chair, Denise J. Smyler.

John M. Donnelly, a Rivers Casino lawyer, said casino staff are trained to ask for identification of any patron who could be underage.

“The rule is that we’re not supposed to let anyone into the casino floor, who doesn’t look 40 years old,” Donnelly said before adding: “I would doubt that 20-year-old looks 40.”

Under the consent agreement, Rivers Philadelphia agreed to “reinforce its existing policies and provide training, guidance and reinforcement to its employees, which will minimize the opportunity for similar incidents to occur in the future.”

But the big mystery, the MacGuffin, went unresolved.

“Sorry,” said Commissioner Frances J. Regan. “Just have to ask: Why did the girlfriend turn him in?”

“I don’t know,” said Donnelly. “I was intrigued by that, too.”

Added Donnelly: “I’m sure it wasn’t a good relationship afterward.”