Nassau County has hired a law firm that plans this month to sue opioid manufacturers in an effort to recoup taxpayer-funded costs of fighting the addiction epidemic.

County Executive Edward Mangano’s administration last week signed a contract with Napoli Shkolnik of Melville, following the county legislature’s approval of the contract in March. The firm will work on a contingency basis, receiving a percentage of any settlements or judgments.

Claims against the drugmakers likely will resemble those that municipalities including Suffolk County have lodged in recent years — that the industry fraudulently and misleadingly marketed prescription painkillers, helping create addicts who moved onto cheaper illicit drugs such as heroin.

The drug abuse, officials argue, has strained local governments by increasing police and social services costs.

“A lot of these manufacturers and distributors haven’t been upfront about what kind of damage these opioids actually do, and because of that, they’ve been overprescribed,” said attorney Salvatore Badala, who will represent Nassau in an action he expects to file this month. “Now we’re seeing what the effects really are.”

A spokesman for Purdue Pharma, a large manufacturer of prescription painkillers, said in a statement: “We share public officials’ concerns about the opioid crisis and we are committed to working collaboratively to find solutions. The delegation of law enforcement authority to a private law firm with a financial interest in the outcome creates serious public policy concerns and presents a clear conflict of interest.”

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Suffolk last year filed suit against 11 pharmaceutical companies and four physicians in State Supreme Court. The case is pending.

Mangano, a Republican, has been researching such a suit for Nassau since early this year. His first attempt to retain a different law firm failed after county legislators questioned how the lawyers would be paid.

The Napoli Shkolnik contract also was tabled initially after one lawmaker questioned the justification for suing opioid makers. It was approved after the administration explained that it was seeking to get back some of the money it has spent battling the addiction crisis.

“Local governments such as the County of Nassau have spent millions of dollars in costs related to opioid addiction and abuse including health care costs, criminal justice and victimization and lost productivity,” Mangano said in a statement. “This litigation seeks restitution from the industry for their aggressive marketing and distribution of opiates.”