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NEW YORK – Silver droplets on the floor of a New York City home provided the first sign that something was amiss.

A further probe into Roman Pinkhasov’s air-conditioning vents, where more of the silver material was found, led to the guy who had installed the units—and now that guy, 48-year-old Yuriy Kruk, has been charged with attempted assault and endangering public health for allegedly trying to poison Pinkhasov and his family, NBC News reports.

The silver substance found in the Pinkhasov home: mercury, or “quicksilver,” per a Department of Environmental Conservation release, which notes Pinkhasov, his wife, and their son had all recently complained of headaches, feeling lethargic, and joint pain. They all tested positive for mercury levels above what’s considered OK.

Queens DA Richard A. Brown pins Kruk’s alleged motive on the fact that he’d installed a heating, AC, and ventilation system in the Pinkhasovs’ Queens home a few years back, and that the family had “persistently complained” one of the AC units wasn’t working. Kruk allegedly told the family he’d have to replace the unit and did so in July 2015.

Pinkhasov’s wife found the droplets right after installation; in August, Pinkhasov found more in the vents and elsewhere where Kruk had worked and called 911. “The victims were merely asking for a repair of their heating and air conditioning units, but instead found themselves fighting for their lives,” says DEC Commissioner Basil Seggos.

The New York Daily News reports Kruk has been released on $10,000 bail and faces up to 15 years behind bars. (How “dancing cats” were the first clue of mercury poisoning in a Japanese town.)

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