"I think many of them were used to get what I call associated intelligence — if they knew somebody who knew somebody who knew somebody," said Emile Nakhleh, the former director of the CIA's Political Islam Strategic Analysis Program who visited the prison to assess detainees there in 2002. "They were the living dots of Google Earth in Afghanistan; we were trying to connect the dots."

The documents, however, undermine Guantánamo's carefully cultivated image as a place where each detainee had been vetted before being sent halfway around the world on a journey for which they were blindfolded, deafened with soundproof headphones and kept in diapers.

Among those held, according to the assessments:

• Haji Faiz Mohammed, a 70-year-old man with senile dementia from Afghanistan's Helmand Province who was detained by U.S. forces during a raid near a mosque where he'd been sleeping. A 2002 memorandum for the commander of U.S. Southern Command, barely more than a page long, said that "There is no reason on the record for detainee being transferred to Guantánamo Bay." Mohammed was shipped home later that year.
• Sharbat, the only name by which he is identified in the records, was arrested by Afghan soldiers after a roadside bomb exploded. His Guantánamo interrogators determined he was an illiterate shepherd who probably was not connected to the explosion. Three interrogation teams at the U.S. detention center at Bagram Airfield also had recommended that he be released. Instead, Sharbat was sent to Guantánamo in November 2003 and held there until February 2006.
• Abdul Salaam's file summarized his case by saying that while he'd initially been accused of being a money launderer for militant groups, "after reviewing all of the available documentation, nothing has been found to support this claim. It is highly probable detainee's statements that he and his family are honest business people ... and have never transferred any money for or on behalf of the Taliban or Al Qaeda are truthful." He was held at Guantánamo from October 2002 to February 2006.
• Khudai Dad may have been a farmer or he may have had a leadership position in the Taliban. It was hard to assess which was true because the schizophrenic was hospitalized at Guantánamo for "acute symptoms of psychosis" after reporting anxiety problems in November 2002 and then referred to the interrogation team for a final session in January 2003.

  Eight months later, Guantánamo personnel judged him ready for a polygraph examination. It didn't last long. Dad began having hallucinations in the middle of questioning and the polygrapher "determined he was mentally unfit." His March 2004 report didn't note how long he'd been at Guantánamo at that point, but Dad wasn't released until February 2006.

There are lingering questions, too, about whether those identified in the assessments as a serious threat really belonged at Guantánamo.

As the post-invasion period began in Afghanistan, militia commanders — some of them with connections to the Taliban and other insurgent groups — began to jockey for power and to place their men in Afghan security units. By all accounts, those men funneled false information about their enemies to U.S. forces.

While the assessments about Afghan detainees did not often record those details, Guantánamo in one instance appears to have housed both a man handed over by a local security commander in eastern Afghanistan, Hafizullah Shabaz Khaul, and then the commander himself, Abdullah Mujahid. They were sent home on the same day in December 2007.

Carol Rosenberg of The Miami Herald contributed to this report.