BND branch office, Bad Aibling © Ulrich Baumgarten/Getty Images

Metadata help America’s intelligence agencies kill. And the BND, Germany’s foreign intelligence agency, is helping the NSA and CIA collect precisely these kinds of metadata. Not in a targeted manner, but on a massive scale. The BND scoops up several million metadata and passes them on to its American counterparts. More precisely: 220 million metadata every day.

A paradigm change is taking place at the BND: Rather than investigating individual suspects, the agency is placing its bets on mass surveillance. Research conducted by ZEIT ONLINE now shows for the first time just how extensive – and troubling – this reorganization is.

It used to be that spies would eavesdrop on people, secretly copy their letters and wiretap their phones. They wanted to know what people were saying, what they were arranging with and disclosing to others. To this day, people have continued to picture surveillance as an agent wearing earphones and listening in. But those days are over.

Today’s spies are interested in completely different traces: metadata. From them, intelligence agencies can deduce who communicated with whom, when, where and for how long. Every email bears such metadata, every text message, every digital image, every WhatsApp message. Whoever can interpret them knows not only what people are telling each other, as metadata betray much more: exactly where people are, where they came from, what they are doing at that moment, even what they are planning. They uncover every hiding place and every secret contact. "We kill people based on metadata," former NSA and CIA head Gen. Michael Hayden said in 2014. Whoever knows the right metadata knows where the deadly drone must be dispatched.

This is precisely what the NSA and CIA are doing. The human targets that American drones pick off with Hellfire missiles in Yemen, Somalia and Afghanistan have been detected using just these kinds of metadata intercepted across the world – with GPS location coordinates, with communication patterns, with cellphone identifiers. Using these pieces of information, one can also compile profiles and recognize patterns in the behavior of targeted individuals. In this manner, intelligence agencies can predict with a high degree of certainty the next move that a certain person will make and where he or she will be at a certain point in time. For the NSA, metadata are one of the most important sources of intelligence.

The BND has also known about the power of metadata for a long time. Since September 11, 2001, officials there have pondered whether to have the agency’s work rely more on such data. Agency files document that these considerations started taking shape beginning in 2002. They also show that, in the meantime, the BND has shifted a major part of its surveillance-related activities to analyzing metadata.

ZEIT ONLINE has learned from secret BND documents that five agency locations are involved in gathering huge amounts of metadata. Metadata vacuumed up across the world – 220 million pieces of it every single day – flows into BND branch offices in the German towns of Schöningen, Reinhausen, Bad Aibling and Gablingen. There, they are stored for between a week and six months and sorted according to still-unknown criteria. But the data aren’t just collected; they are also used to keep tabs on and track of suspects.

Exactly where the BND obtains the data remains unclear. The Bundestag committee investigating the NSA spying scandal has uncovered that the German intelligence agency intercepts communications traveling via both satellites and Internet cables. The 220 million metadata are only one part of what is amassed from these eavesdropping activities. It is certain that the metadata only come from "foreign dialed traffic," in other words, from telephone conversations and text messages that are held and sent via mobile telephony and satellites.