HOWELL - Men and women with guns, white suits and gas masks swarmed a Birdsall Road home Tuesday. The house is linked to a woman who, authorities say, helped sell a lethal dose of synthetic opioids online.

Law enforcement officers were not immediately able to confirm the connection.But public records show the house is the address of 29-year-old Victoria Koleski, who is facing drug dealing charges along with 34-year-old Brian Parker of Long Island City, New York.

The U.S. Attorney's Office for the District of New Jersey announced the charges against Koleski and Parker in a prepared statement Tuesday.

Parker has already been convicted of federal drug crimes, pleading guilty in 2011 in Pennsylvania in another scheme to sell drugs online, according to a criminal complaint against him.

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The investigation dates back to May 22, 2016, when police in Madison, Wisconsin, first got a report of a 37-year-old man who had stopped breathing, according to the statement from Matt Reilly, a spokesman for federal prosecutors in New Jersey. The man died before police arrived, and an autopsy showed that an overdose on a synthetic opioid and benzodiazepine had killed him.

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The opioid, U-47700, "is several times more potent than morphine," Reilly said.

Authorities found mailing materials, vials of the drug and "multiple invoices indicating the victim had been ordering U-47700 and other substances from a website run by Parker," Reilly said.

Parker and his crew had been buying "raw materials from China and elsewhere," making designer drugs and selling them online, Reilly said. "For example, from June 30, 2017 through July 5, 2017, Koleski shipped approximately 218 parcels from a post office located in Farmingdale, many of which contained controlled substance analogues that Parker sold online."

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Parker had been selling through two websites, unbeatablechems.com and rcpowders.com, according to a criminal complaint sworn out by U.S. Drug Enforcement Administration Task Force Officer David J. Formalarie. The websites advertise Parker's products as "research liquids" and "research powders."

Parker used "social media websites such as 'Reddit' to discuss his controlled substance analogue business," Formalarie wrote. Several subreddits are devoted to discussing "research chemicals" and where to order them.

An undercover agent bought drugs online from Parker's websites, paying him through Venmo and money orders, according to the complaint.

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Besides benzos and opioids, Parker and Koleski were selling designer versions of alpha-Pyrrolidinopentiophenone (A-PVP, or "flakka"), a euphoria-inducing stimulant, and phencyclidine (PCP), a dissociative drug, prosecutors said.

Federal drug investigators, state troopers and township police went to the Birdsall Road home Tuesday, along with medics and firefighters.

Koleski and Parker made their first appearances in federal court in Newark Tuesday. Each is facing charges of drug distribution, possession with intent to distribute and conspiracy. Prosecutors said they remained in custody pending a future bail hearing.

Koleski's address is geographically in Howell but is listed as Farmingdale.

Check out the video at the top of this story to see investigators who appear to go through a decontamination process upon leaving the house.

Alex N. Gecan: 732-643-4043; agecan@gannettnj.com