MICHELE NORRIS, host:
This week, we've been reporting on hundreds of classified documents about the detainees held at Guantanamo Bay. The files are part of a secret cache obtained by the group WikiLeaks. Most of this collection comes from the military's joint taskforce at Guantanamo. That team was responsible for figuring out which detainees were al-Qaida members and a threat, and which were not.
As NPR's Dina Temple-Raston reports, interrogators often had to make big decisions based on tiny clues.
DINA TEMPLE-RASTON: If al-Qaida could learn anything from these latest classified documents, it would be lose the Casio watch - specifically a Casio F-91W, either plastic or silver bracelet. That specific watch was mentioned nearly 150 times in the Guantanamo prisoner assessments. And if you have one, you're suspect.
A footnote in one file claims the watch was given to graduates of al-Qaida's explosives training program in Afghanistan. And it's apparently a good bomb timer because its alarm can be set beyond a 24-hour period. Footnotes in the document say that Pakistani officials found more than 600 of the watches in a terrorist safe house in Karachi. Knowing all that, the challenge is to figure out when a watch is just a watch or when it signals a link to terrorism.
Mr. JIM CLEMENTE (Supervisory Special Unit, FBI): One of the methods utilized to verify information gathered from detainees in this situation or any situation is cross corroboration.
TEMPLE-RASTON: That's Jim Clemente. He was in charge of the FBI's behavioral analysis unit at Guantanamo. He taught interrogators to build rapport with prisoners so they would volunteer information, including information about why they had those watches.
Mr. CLEMENTE: You have to test that information, and you verify or refute it by testing it on other people. A lot of it is basically based on rumor and innuendo, and then you build a consensus of information.
TEMPLE-RASTON: One of the documents in the secret files is an 18-page primer of what interrogators should look for. It's a list of things that should arouse suspicion - subtle, spy vs. spy clues. The document was called "The Matrix of Threat Indicators," and the Casio is one item on the list. The problem, of course, is that simply possessing a Casio watch doesn't prove anything.
Consider Detainee 194, a Libyan named Muhammad al-Rimi. When he was picked in up 2001, there were two suspicious indicators - 18 $100 bills in his pocket and a Casio F-91 strapped to his wrist. The $100 bills had serial numbers in sequence with money found on admitted al-Qaida members. And as for the Casio, his file reads: This watch has been linked to al-Qaida in the past.
Clemente says what they found on al-Rimi was enough to warrant more questions, but not enough to build a legal case.
Mr. CLEMENTE: Intelligence gathering doesn't have the same restrictions on it as criminal prosecution does. And in this case they mixed the two.
TEMPLE-RASTON: Even though al-Rimi's file says he was never specifically linked to explosives, because he had the watch, the file concludes: the possibility warrants further interrogation. Al-Rimi was transferred to Libya in 2006.
In Guantanamo's early days, the focus was on gathering intelligence. Now, with the Obama administration trying to close the prison, evidence for prosecution has become more important.
Karen Greenberg is the executive director of the Law and Security Center at New York University. She says the problem is that U.S. officials can't easily use raw intelligence, like the watches, as evidence in court.
Professor KAREN GREENBERG (Executive Director, NYU Law and Security Center): If there had been more evidence on them, the entire question of Guantanamo and whether or not to try them would have been much easier because with evidence, and reliable substantial evidence, there is no question that there can be trials.
TEMPLE-RASTON: Other indicators in the secret threat document listed as suspicious - walkie-talkies. Being captured with one was significant. The reasoning? There weren't many radios to go around, so the only people who got them were those in leadership positions. Going to Afghanistan or Pakistan to find a wife? That, apparently, was a common al-Qaida cover story.
What the classified Guantanamo files don't acknowledge is that very often, young Muslims - with no links to al-Qaida at all traveled to Afghanistan or Pakistan to find wives or that Casio watches are sold in just about every street market in South Asia.
Dina Temple-Raston, NPR News.