N.J. books pretty much know all about you even before you bet

ATLANTIC CITY, N.J. — Kevin Duffey and his small team spend most of their days in a cramped, windowless bunker tucked off a third-floor hallway at the Resorts Casino. As the casino’s director of surveillance, Duffey keeps watch over the vast gambling operation through 29 high-definition video screens along the walls that process images from more than 1,000 cameras anchored throughout the building.

Three flights below, a group of bettors mingled around a kiosk in a gleaming sports book operated by Draftkings, a sports gaming company. A camera directly above the kiosk projected the group’s last-minute betting debate to Duffey’s monitors upstairs.

A scar on one of the men’s eyebrows, visible from under his hooded sweatshirt, was captured by one of the high-resolution cameras that are built into every ticketing window and kiosk here.

“We’re watching behind the scenes,” said David Rebuck, director of the New Jersey Division of Gaming Enforcement, who was also in the room with Duffey.

“He thinks he’s anonymous. But he’s not anonymous.”

As sports betting has boomed from a niche hobby to big business in New Jersey, so too has the high-stakes battle to protect the integrity of professional and collegiate games — and the betting systems themselves.

With more than $600 million wagered since sports betting became legal in June, operators have begun using a range of policing and data-gathering methods to ferret out would-be swindlers. There are surveillance rooms at casinos, data-col-