Defenders of the American government's online spying program known as "PRISM" claimed Friday that the suddenly controversial secret effort had saved New York City's subways from a 2009 terrorist plot led by a young Afghan-American, Najibullah Zazi.

But British and American legal documents from 2010 and 2011 contradict that claim, which appears to be the latest in a long line of attempts to defend secret programs by making, at best, misleading claims that they were central to stopping terror plots. While the court documents don't exclude the possibility that PRISM was somehow employed in the Zazi case, the documents show that old-fashioned police work, not data mining, was the tool that led counterterrorism agents to arrest Zazi. The public documents confirm doubts raised by the blogger Marcy Wheeler and the AP's Adam Goldman, and call into question a defense of PRISM first floated by House Intelligence Committee Chairman Mike Rogers, who suggested that PRISM had stopped a key terror plot.

Reuters's Mark Hosenball advanced the claim Friday, based on anonymous "government sources":

A secret U.S. intelligence program to collect emails that is at the heart of an uproar over government surveillance helped foil an Islamist militant plot to bomb the New York City subway system in 2009, U.S. government sources said on Friday.



The sources said Representative Mike Rogers, chairman of the House of Representatives Intelligence Committee, was talking about a plot hatched by Najibullah Zazi, an Afghan-born U.S. resident, when he said on Thursday that such surveillance had helped thwart a significant terrorist plot in recent years.



President Barack Obama's administration is facing controversy after revelations of details of massive programs run by the National Security Agency for collecting information from telephone and Internet companies.



The surveillance program that halted the Zazi plot was one that collected email data on foreign intelligence suspects, a U.S. government source said.

The New York Times also emphasized the Zazi case Friday:

To defenders of the N.S.A., the Zazi case underscores how the agency's Internet surveillance system, called Prism, which was set up over the past decade to collect data from online providers of e-mail and chat services, has yielded concrete results.



"We were able to glean critical information," said a senior intelligence official, who spoke on the condition of anonymity. "It was through an e-mail correspondence that we had access to only through Prism."

But public — though not widely publicized — details of the Zazi plot cast into doubt the notion that a data mining program had much to do with the investigation. Zazi traveled to Pakistan in 2008 to train with al Qaeda. He was charged in 2009 with leading two other men in a plot to detonate suicide bombs in the New York subways.

The path to his capture, according to the public records, began in April 2009, when British authorities arrested several suspected terrorists. According to a 2010 ruling from Britain's Special Immigration Appeals Commission, one of the suspects' computers included email correspondence with an address in Pakistan.

The open case is founded upon a series of emails exchanged between a Pakistani registered email account sana_pakhtana@yahoo.com and an email account admittedly used by Naseer humaonion@yahoo.com between 30 November 2008 and 3 April 2009. The Security Service's assessment is that the user of the sana_pakhtana account was an Al Qaeda associate..."

"For reasons which are wholly set out in the closed judgment, we are sure satisfied to the criminal standard that the user of the sana_pakhtana account was an Al Qaeda associate," the British court wrote.

Later that year, according to a transcript of Zazi's July, 2011 trial, Zazi emailed his al Qaeda handler in Pakistan for help with the recipe for his bombs. He sent his inquiry to the same email address: sana_pakhtana@yahoo.com.

An FBI agent, Eric Jurgenson, testified, "I was notified, I should say. My office was in receipt of several e-mail messages, e-mail communications." Those emails — from Zazi to the same sana_pakhtana@yahoo.com — "led to the investigation," he testified.

The details of terror investigations are not always laid out this clearly in public; but they appear to belie the notion, advanced by anonymous government officials Friday, that sweeping access to millions of email accounts played an important roil in foiling the subway attack. Instead, this is the sort investigation made possible by ordinary warrants under the Foreign Intelligence Surveillance Act; authorities appear simply to have been monitoring the Pakistani email account that had been linked to terrorists earlier that year.

This was, in fact, reported at the time. That November, British authorities were bragging to the Telegraph about their role in arresting Zazi:

The plan, which reportedly would have been the biggest attack on America since 9/11, was uncovered after Scotland Yard intercepted an email....The alleged plot was unmasked after an email address that was being monitored as part of [the 2009 U.K. case] was suddenly reactivated.

The existence of PRISM was revealed Thursday by the Washington Post and the Guardian. Authorities are now scrambling to justify the program.