Yale Law School Professor Steven Duke made a career out of counseling prison inmates. Now he is trying to free one of New Jersey’s most notrious mobsters.

Duke scored a victory Tuesday when the New Jersey Superior Court compelled Thomas Ricciardi, who claims his affidavit attesting to the innocence of Duke’s client — reputed mob boss Martin Taccetta — is forged, to testify in court. Ricciardi’s affidavit affirms Taccetta’s innocence in the murder of Vincent J. “Jimmy Sinatra” Craparotta, which occurred at Craparotta’s auto dealership in Dover Township, N.J. more than a decade ago. But the New Jersey Division of Criminal Justice claims that three affidavits Duke submitted in July, which are purportedly signed by Ricciardi, his wife and his brother, are fraudulent.

Ricciardi and Taccetta — who is currently incarcerated in Trenton’s New Jersey State Prison — were both convicted of racketeering, extortion and murder in connection with Craparotta’s death, and the affidavits could be key evidence in overturning Taccetta’s 30-years-to-life conviction.

An inquiry into the alleged forgeries is ongoing, said New Jersey Assistant Attorney General Robert Leaman, the lead prosecutor in the case.

“We will continue our investigation into potential criminality and follow the facts wherever they lead us, even if that’s to the steps of New Haven,” he said.

Ricciardi came to Yale this summer to sign the affidavit, which was notarized by Duke’s assistant. Duke, who has not being charged with any wrongdoing, said he has witnesses who will affirm that Ricciardi was physically present in New Haven.

“I’m prepared to defend it,” Duke said.

Leaman alleges that Ricciardi and his wife and brother were not in Connecticut on July 17, 2005, the date the affidavit was signed. Leaman said the court order for Ricciardi’s testimony could jeopardize his safety because Ricciardi is currently in a witness protection program and lives in a community where people are not aware of his criminal past.

“It would put him in great physical jeopardy to be brought back here,” Leaman said.

The alleged forgeries has not yet produced a clear suspect, although authorities believe a crime was committed, Leaman said.

“Often it happens in a criminal case that someone’s lying and someone’s telling the truth,” Duke said. “There will be a determination in a couple of months of who’s lying.”

Duke, professor of Science and Technology at the Law School, has taught at Yale for more than 40 years and currently teaches a criminal law course called “Convicting the Innocent.” In 2001, he represented former Saybrook College Master Antonio Lasaga in front of the Yale Corporation, which upheld a decision to revoke Lasaga’s tenure after he admitted to possessing child pornography. Lasaga is currently serving a 15-year sentence for that offense concurrently with another 20-year sentence for the sexual assault of a minor.