NEW YORK (CBSNewYork) — New York police recovered four kilograms — nearly nine pounds — of the deadly narcotic fentanyl wrapped inside fish and other food in the Bronx last week.

NYPD’s Queens Narcotics Major Case Squad detectives had been watching a 2017 white Acura MDX with two boxes in the back seat near the intersection of Leland Avenue and Archer Street in the Parkchester neighborhood of the Bronx.

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Johnny De Los Santos-Martinez was arrested Feb. 1, 2018.

According to police, the narcotics were initially suspected to be cocaine, but lab tests revealed them to be fentanyl, an illicitly produced synthetic opioid that is up to 50 times as strong as heroin.

Inside both boxes were Styrofoam coolers containing fish wrapped around two brick-shaped packages covered in green plastic, with a third brick-shaped package concealed in a vacuum-sealed package of what appeared to be chili. A second cooler contained one brick-shaped package similarly wrapped with green plastic and fish.

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“It was like a fish sandwich,” said Bridget Brennan, the city’s special narcotics prosecutor. “If they use something like very smelly fish that might conceal the odor of something like fentanyl.”

Police said the amount of recovered could have yielded more than a million lethal doses worth up to $10 million dollars on the street. The wholesale value for four kilograms of fentanyl is estimated at $100,000.

Fentanyl is increasingly being mixed into the black market drug supply in New York City and is frequently found in combination with heroin, cocaine and a variety of synthetic drugs.

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De Los Santos-Martinez was arraigned in Manhattan Criminal Court.