It was a culinary whodunit involving a daring heist, a golden bounty, and now, some allegedly sticky-fingered suspects.

Police in Quebec announced the arrest of three men in the theft of 6 million lbs. of maple syrup from a provincial warehouse, a haul estimated at $18-million and enough to smother a Himalayan mountain of waffles and pancakes.

The arrests mark a badly-needed break in a case that circled the globe and pulled in law-enforcement agents operating in two countries and three provinces, all deployed in the retrieval of one of Canada’s most cherished resources.

The theft was discovered in August at a depôt rented by the Quebec Federation of Maple Syrup Producers, in what police believe was an inside job. Some 10,000 barrels of stockpiled syrup, part of the federation’s carefully guarded “International Strategic Reserve,” had gone missing. The Fort Knox-style controls reflect the fact that Quebec dominates the world market in maple syrup and carefully controls the commodity’s price and supply.

“One of the suspects clearly had access to the warehouse,” said Lt. Guy Lapointe of the Sûreté du Québec. He said the looted liquid was then transferred within the warehouse in St.-Louis-de-Blandford to waiting trucks. “Because they were doing it inside, they couldn’t be seen from outside, and it was easier for them to steal the syrup.”

Some of the syrup found its way to buyers outside Quebec, some of whom may not have been aware it was stolen, Lt. Lapointe said. The objective for the perpetrators, however, was straightforward. “The whole point was to make some money.”

Two of the three suspects were led into a Quebec courthouse in handcuffs under a heavy snowfall in Trois-Rivières on Tuesday. Richard Vallières, 34, and Avik Caron, 39, face charges of theft, conspiracy, fraud and trafficking in stolen goods.

The operation was vast. Investigators interrogated nearly 300 people and executed search warrants in New Brunswick, Ontario and the United States. They seized vehicles they suspect are linked to the theft, along with equipment such as electronic scales, industrial lifts, and kettles used in syrup production. In addition to province police, the effort involved the RCMP, Canada Border Services Agency, as well as U.S custom and immigration agents, whose investigation is centered in Vermont, according to a spokesman for the Department of Homeland Security.

Police say the theft from the squat brick warehouse off a highway in St. Louis-de-Blandford, southwest of Quebec City, took place sometime between August last year and July this year. Provincial police went as far as posting online the photos of five people from Quebec under the title “Wanted,” who are the object of arrest warrants in the case. One warrant targets a woman from Bécancour, Que. on charges of fabricating a forged waybill to dupe U.S. and Canadian border agents.

Police say two thirds of the missing syrup has been located, some of it in the northern U.S. But while some barrels of retrieved syrup is under provincial police guard, some remains outside the province.

“Police know where it is, now we’re trying to recover it,” said Simon Trépanier, interim director of the Quebec maple syrup federation. “But we have to identify its ownership, because nothing resembles a barrel of maple syrup like another barrel of maple syrup.”

The stakes in the syrup caper are high: Quebec produces about 80 percent of the world’s syrup, and the missing loot represented about 12 per cent of the federation’s inventory. While the theft is not expected to affect supplies in Canada, one industry insider said the appearance of black-market syrup may have been responsible for a decrease in the price being sought by buyers in some European markets.

Part of the haul might is alleged to have been sold to a New Brunswick maple export business, where police executed a search warrant in September and hauled away enough barrels to fill six truckloads.

Étienne St-Pierre, owner of S.K. Export Inc. in Kedgwick, N.B., said he had purchased the syrup from a regular supplier, Richard Vallières, but didn’t know it had a suspicious origin.

“You bring me syrup, it’s syrup. There’s no serial number on it,” Mr. St-Pierre said.

Sarto Landry, a lawyer for the Richard Vallières who had sold syrup in New Brunswick, declined to comment.

In a past interview, before the arrests, Mr. Landry had said his client purchased the product at regular prices and had no inkling it could have been stolen.

He said the police had been visiting producers and asking them to submit to lie detectors.

Mr. St-Pierre has said in the past that he and his suppliers have been unfairly targeted by Quebec authorities for transacting outside of the Quebec federation of maple producers.

In Quebec, the production and sale of maple syrup, like other farm products, is regulated by a marketing board, the Régie des marchés agricoles et alimentaires du Québec, which sets prices and quotas for bulk sales.

“It’s like a legal cartel,” said Benoît Girouard, president of L’Union Paysanne, a farmers’ group opposed to the marketing board.

Sales of small bottles of syrup on the premises is not restricted but for any larger amounts, farmers have to declare their harvest and remit it to the federation, which warehouses the product and resells it, Mr. Girouard said.

This has led to inflated prices and a syrup black market, he said, noting that small and medium-sized producers are being squeezed out by the system’s quota restrictions.

Disputes involving maple producers are among the most common complaints in tribunal decisions by the Régie.

Rulings describe how producers getting fined for failing to declare their production fully and how officials have sent inspectors to sugar bushes to check whether the number of maple tap holes matched the reported sap output.

“There’s a total loss of control of your harvest,” Mr. Girouard said. “We’re not talking about regulating. It’s policing and it’s nonsense.”