Twenty-five people have been accused of a conspiring to sell heroin in a ring that reached from Mexico to Suffolk County, New York Attorney General Eric T. Schneiderman said Friday.

The heroin was smuggled into the United States in cars, buses and other vehicles, said Schneiderman, whose office seized 33 kilograms of heroin and other illicit drugs with a street value of more than $13 million.

Authorities said the drugs were stashed in hidden compartments in the vehicles, which passed through Tucson, Arizona, and made their way across the Eastern Seaboard, including the Bronx and Massachusetts.

The investigation was spurred by a Long Island-based State Police trooper’s lament about heroin trafficking and overdoses in Brentwood, Schneiderman’s office said.

“Long Island is facing a very severe heroin and opioid problem,” Schneiderman said in Manhattan. “It was pretty much a countywide problem. It started off in Brentwood, but it was a huge problem out there.”

The investigation, named “Operation Dirty Dope,” started with a tip from a confidential informant, which led to wiretaps of 46 phone lines, according to an attorney in Schneiderman’s office who spoke on condition of anonymity.

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The seized drugs were mixed with nail polish remover, Novocain, chicken anesthetic or boric acid, Schneiderman said. Adding impurities is a way of padding the product without using more expensive heroin and can be lethal.

Among the items seized by Schneiderman’s team: a gun with the logo of the Mexican Sinaloa cartel, which allegedly is linked to the drug pipeline.

So far, agents have arrested 19 of the 25 defendants charged in the 98-count indictment, handed up Monday in the Bronx.

Three Suffolk defendants — Luis Aude-Mora, 26, of Bay Shore; Amauris Sanchez, 32, of Brentwood, and Oscarhyl Martinez Aude, 31, of Brentwood — have been arrested.

Another defendant, Manuel Torres of Port Washington remains at large, and another named in the case, Nelfi Aude, 30, has since died. He was found dead in his apartment, with the cause as yet undetermined, the attorney said.

Legal counsel for the defendants could not be reached for comment.