Authorities say they’ve disrupted a heroin pipeline that stretched from Pittsburgh to New York City and Long Island in an investigation that led to seven arrests and prevented up to $1 million in drugs from hitting the streets.

Some of the heroin seized from the large-scale illicit drug operation was found to be at least three times more pure than usual, Nassau District Attorney Madeline Singas said Monday.

She called the ring’s product “very deadly and very potent.”

The arrests followed a four-month joint probe by agencies including Nassau police and prosecutors, a Drug Enforcement Administration local task force and Port Authority police.

Law enforcement officials identified Victor McKeever, 53, of Pittsburgh, as the ring’s alleged leader, saying the operation used a stash house in Kew Gardens, Queens, to funnel heroin to places including Freeport in Nassau County.

Among other defendants facing charges is Freeport resident Donna Martin, 51, authorities said.

Acting Nassau Police Commissioner Thomas Krumpter said fentanyl, which also was seized, was used as a cutting agent in some of the heroin.

McKeever was arraigned last Thursday before acting Supreme Court Justice Meryl Berkowitz on felony charges including operating as a major trafficker and first-degree criminal possession of a controlled substance.

He pleaded not guilty and bail was set at $1 million bond or $500,000 cash. McKeever is due back in court on July 12.

He faces a maximum of 25 years to life in prison if convicted on the top count. He was arrested in December and was extradited by Nassau County police last week, police said.

His attorney Jason Russo, said Monday that his client had fought extradition and previously had never been to Nassau County.

“I intend to fight this every step of the way,” Russo said. “He says he has absolutely nothing to do with these charges and these events.”

With Gary Dymski