Nassau County will appeal a federal jury's award of $18 million each to two men who were exonerated in the 1984 murder and rape of a Lynbrook teenager after serving nearly 18 years in prison, an official said.

County spokeswoman Katie Grilli-Robles said Friday that Nassau also plans to challenge a 2013 ruling overturning an earlier jury decision that cleared the county and its police department of wrongdoing in the criminal case.

"We fully expected them to appeal," said Nick Brustin of Manhattan, the lead lawyer for the men. "We are very confident of the verdict, and eventually the court will force them to do what they should have done on their own."

Last week, in the first phase of the civil trial, jurors decided that the civil rights of John Restivo, 56, and Dennis Halstead, 59, had been violated by now-deceased Nassau County homicide Det. Joseph Volpe because he planted and withheld evidence.

Restivo and Halstead were released in 2003 after newly discovered DNA evidence from sperm in 16-year-old victim Theresa Fusco's body did not match their own.

Concetta Napoli, Fusco's mother, still believes the men are guilty, and spoke out Thursday in support of an appeal.

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Also backing the legal challenge is the detective's sister, Carol Volpe Hessemann.

"My brother would never have done such a thing," Hessemann, of North Massapequa, said Friday. "He was good-hearted."

In an earlier federal civil rights case, a jury in Central Islip decided in November 2012 that Nassau police committed no wrongdoing in the investigation that led to Restivo's and Halstead's imprisonment.

But in July 2013, U.S. District Judge Joanna Seybert overturned the decision, leading to the trial and $36 million award.

In her ruling, Seybert said the first jury had been wrongly allowed to hear the confession of a third person, John Kogut, who was also convicted in the murder. The confession, later found to be false, was not admissible as evidence during Restivo's and Halstead's trial.

Without a "nuanced" explanation of the law, Seybert said in her decision, the 2012 civil jury should not have been allowed to think the confession helped officials in charging Restivo and Halstead.

Kogut, also exonerated in the rape-murder, is appealing a decision excluding him from this month's civil trial.