Attorney Mark S. Zaid meets with his client Sabrina De Sousa at a local restaurant in Tysons Corner. De Sousa was convicted for her role in the abduction of Abu Omar in 2003 in Milan. (Nikki Kahn/The Washington Post)

The CIA and U.S. military officials appealing their convictions before the Italian Supreme Court on charges of kidnapping a terrorist suspect in Milan must wait until September for a possible final verdict in the long-running case.

The Supreme Court of Cassation in Rome on Saturday postponed until Sept. 19 its highly anticipated ruling, which will determine the fates of two Washingtonians, Sabrina De Sousa, a former CIA operative, and Col. Joseph L. Romano III, a retired Air Force commander.

Italian prosecutors also asked the court to dismiss Romano’s charges, saying he deserved immunity, according to U.S. officials familiar with the proceedings. For De Sousa and the other Americans, Italian prosecutors asked that their cases be sent to another appeals court for the examination of potential procedural defects.

The case is considered significant because a foreign country — an ally — prosecuted and convicted U.S. officials for the practice of rendition, in which a terrorist suspect is flown against his will to another country for interrogation. The case also tests the relationship between the United States and Italy and whether the Western ally will ultimately honor the U.S. assertion of immunity for Romano under the NATO Status of Forces Agreement.

De Sousa and the other convicted CIA officials were never given diplomatic or consular immunity.

On Feb. 17, 2003, an Egyptian cleric, Hassan Mustafa Osama Nasr, known as Abu Omar, left his Milan apartment and vanished. Italian prosecutors in 2009 convicted 23 Americans — nearly all of them alleged CIA operatives — for their alleged role in his abduction.

Italian prosecutors allege in court papers that De Sousa was a “CIA agent” attached to the Milan Consulate in 2003who helped orchestrate the kidnapping. De Sousa denies that she served as a CIA officer and says she was registered as a State Department officer in Milan. She says she had nothing to do with the rendition and was chaperoning her son’s school ski trip that day.

Romano has been accused of helping smuggle the CIA kidnapping crew and Omar onto Aviano Air Base in northeast Italy, from which Omar was flown to Germany, then on to Egyptfor interrogation.

All the Americans were convicted in absentia. None have been extradited to Italy. Romano and De Sousa say the charges against them are highly circumstantial.

“I’m confident the court will, following [the prosecution’s] insightful comments and persuasive arguments by my attorneys Mr. Cesare Bulgheroni and Professor Luigi Fornari, render a decision that upholds the sanctity of the NATO treaty,” Romano said Saturday. “By doing so, the court will strengthen Italian relations with the U.S. and better protect those defending NATO nations, such as Italy, against forces who advocate harm against them.”

De Sousa said she was heartened that the Supreme Court appeared to want to scrutinize what she views as weak evidence against her. But she said also worries prosecutors are dragging the case out by asking the court system to review procedural questions she believes could have been resolved years ago.

“What really should be investigated in Italy and the U.S. is: What case was made to render Omar in the first place?” De Sousa said.