Defense Cites Ambiguities in Evidence Against Padilla

A CIA agent, identified by his alias "Tom Langston," was allowed to testify in light disguise -- a wig, a beard and glasses.

Langston testified about serving in Kandahar, Afghanistan, and receiving the truckload of documents from the Afghan man. The man told him that he had picked up the documents from an office that had been used by Arabs, Langston testified.

But where exactly did the Afghan man find them? Why did he bring them to the U.S. side?

Langston was not allowed to disclose the contact's tribal affiliation, let alone his name.

"He was loyal to some individuals who were cooperating with us against the Taliban and the terrorist elements," Langston testified. "I think he took this initiative on his own."

Given the ambiguities in the appearance and origins of the form -- nothing explicitly links it to Padilla or to al-Qaeda -- the struggle for prosecutors is to make those connections using other testimony.

Among the key links are seven fingerprints that the authorities lifted from the application form.

A U.S. fingerprint expert testified that a 2006 analysis identified Padilla's fingerprints on the front of the first page of the form and on the back of the last page.

Defense attorneys have questioned why Padilla's prints do not appear on the middle pages of the application form. They have suggested that the prints' locations are consistent with Padilla being handed the form during his detention, and not opening it.

But there is no way of knowing when those prints were made, the fingerprint expert said.

The form, defense attorney Anthony Natale told jurors this week, is a "questionable document."

He warned them against believing the prosecutors who, he alleged, had allowed the atmospherics of the case -- the associations with al-Qaeda and bin Laden -- to make a weak set of facts look stronger than it is.

"In the absence of hard evidence, a suspicion can be fueled by fear, nourished by prejudice and directed by politics into a criminal prosecution," he said.