Still, there’s much that’s unknown about what happened in the Markus Wolf villa: the role of outside contractors in the prison’s day-to-day operations, the discussions between intelligence agencies that led to the establishment of the prison and what the Poles received in return, if anything, for allowing the black site to operate.

Evidence emerges in bits and pieces, in newspaper reports, in cryptic utterances from the state prosecutor and in the revelations of Jozef Pinior, a member of the Polish Senate and the European Parliament, who’s the one senior politician who’s consistently championed the case. In June, he said he’d seen an order to build an iron cage and deliver it to the villa.

His newest anecdote about the CIA prison centered on a note he’d seen from Polish intelligence officials to CIA personnel at the intelligence compound. It urged them not to throw any more kielbasa or Polish sausage in the trash, lest people think that Muslims are being held at the Stare Kiejkuty villa. “It is a clear message for people in the village that people are being held there.”

Journalist Adam Krzykowski, who in 2009 discovered many of the flight records and a computer hard disk that had eluded previous investigators, estimates that six to eight suspects, at most 11, were detained at Stare Kiejkuty. Altogether, there were seven special CIA flights to Szymany, an airport about 15 miles away, according to the flight records Krzykowski turned up, with the first arriving from Bangkok on Dec. 5, 2002, with seven passengers, and the last one out in September 2003 with five passengers.

Ironically, it was an official visit to Poland by President George W. Bush in June 2003 that led to the closing of the villa. Bush’s thanks for Poland’s cooperation in the war on terrorism were “so profuse” that the Polish president, Kwasniewski, realized “something was not right,” Gazeta Wyborcza reported in June 2011. He ordered an investigation, and on learning that the CIA was flying suspects into Poland for interrogation, ordered the interrogation center closed.

Where the prosecution goes from here isn’t clear. Pietrzak, Nashiri’s Polish attorney, thinks the Tusk government wants to string out the process. “If they charge someone there will be an eruption,” he said.

But others think that however long it takes, the Polish investigation won’t go away.

“For better or worse, there have been too many leaks about what is going on inside that prosecution,” said Crofton Black, a senior investigator at the British prisoner advocacy group Reprieve. “Even if it weren’t very difficult to walk away at this stage, so many documents have been sent to or seen by the prosecutor, so much is in the public domain. The cat’s out of the bag now.”

Carol Rosenberg of The Miami Herald and McClatchy special correspondent Barbara Dziedzic contributed to this report.