Government officials say the recently revealed PRISM spying program is an essential terrorist-catching tool, and defenders are pointing to a foiled 2009 plot to bomb the New York subway system as evidence of its utility. But some journalists are questioning whether the broad spying program actually played a role in the capture of would-be subway bomber Najibullah Zazi.

The New York Times set the scene in a story Friday. “In early September 2009, an e-mail passed through an Internet address in Peshawar, Pakistan, that was being monitored by the vast computers controlled by American intelligence analysts,” reporters Eric Schmitt, David Sanger and Charlie Savage wrote. “It set off alarms.”

An anonymous intelligence official told the Times that the government had access to the email correspondence between Zazi and the Pakistan address only through PRISM. Citing anonymous government sources, a Reuters article echoed the claim that the PRISM program helped nab Zazi, an Afghanistan-born U.S. resident.

But some media outlets are questioning the government version of the story. The trail that led to Zazi through the email address may have been more dependent on British policework than on PRISM. In April 2009, Britain hastily arrested about a dozen men of Pakistani origin as part of a counterterrorism effort called Operation Pathway. (The haste was necessitated by the fact that a counterterrorism official, Bob Quick, was photographed walking into the British prime minister’s office with top-secret documents.)

On Friday, BuzzFeed pointed to a 2010 ruling by a British immigration appeals panel that indicates that the Pakistani-registered email address was already identified as belonging to an al Qaeda associate. The email was being monitored by U.K. intelligence as part of Operation Pathway, according to the Telegraph.

At Zazi’s trial in 2011, FBI agent Eric Jurgenson testified that it was Zazi’s emails to sana_pakhtana, seeking help with bomb-making, that led to the initial investigation, BuzzFeed noted.

“Court documents don’t exclude the possibility that PRISM was somehow employed in the Zazi case, [but] the documents show that old-fashioned police work, not data mining, was the tool that led counterterrorism agents to arrest Zazi,” BuzzFeed’s Ben Smith wrote.

Then again, British intelligence may have gotten wind of the Pakistan email account through PRISM. The Guardian reported Friday that the U.K. Government Communications Headquarters, or GCHQ, its electronic monitoring agency, had access to the U.S. spying program since at least June 2010.

Another version of the investigation sources the beginning of the investigation of Zazi to a tip from Pakistani intelligence. An October 2009 NPR piece, citing unnamed law-enforcement sources, said Pakistan notified the U.S. that Zazi was meeting with al Qaeda operatives inside the country in 2008. After that, NPR said, the FBI applied for an OK of a roving wiretap under the Foreign Intelligence Surveillance Act. This wiretap allowed it to keep tabs on Zazi through a range of communications: cellphone conversations, emails and text messages.

The FBI wiretap picked up phone conversations about bomb-making. That led to physical surveillance and, eventually, Zazi’s arrest in New York.

So what really led to the capture of Najibullah Zazi? A sweeping U.S. government email spying program? British policework? British policework, relying on a sweeping U.S. government email spying program? A tip from Pakistan? The exact timeline and narrative of the Zazi case isn’t quite clear yet, but it’s a rare glimpse into the murky world of counterterrorism for the public.