What did the German chancellor's office know? That's what's a parliamentary investigative committee is looking into as it conducts its final public interviews in the aftermath of the the whistleblower Edward Snowden's 2013 revelations that the US's National Security Agency (NSA) had spied on German and EU citizens - including Angela Merkel - with the cooperation of the foreign intelligence service, the BND.

On Monday, the committee questioned the state secretary for intelligence affairs in the chancellor's office, Klaus-Dieter Fritsche, for over four hours. In some respects, the session was a warmup for Thursday, when Merkel herself will appear before Bundestag deputies. All indications are that she's in for a rough ride.

"So, who dropped the ball?" committee chairman Patrick Sensburg, a member of Merkel's conservative Christian Democrats, pointedly asked Fritsche. "My impression is that our conglomeration of search terms wasn't adequately maintained at all."

In 2013, it emerged that the NSA was using so-called selectors targeted at EU citizens in data that the BND had helped procure. That, critics say, violated Germany's constitutionally guaranteed individual right to privacy of communication. Fritsche passed the blame on to the BND, saying there had not been adequate checking of the hundreds of thousands of selectors the NSA had presented to their German colleagues.

Fritsche repeatedly answered questions by saying he hadn't been in his current office at the time of the spying. His position within the chancellor's office was specially created in March 2014, and he said things had gotten better since. But that wasn't enough to satisfy parliamentarians.

Sensburg, a conservative, led the tough questioning

Embarrassments all around

When the scandal broke in 2013, German politicians and the public were shocked at the idea that a close ally like the United States was eavesdropping on them. Even Merkel's cellphone had reportedly been subjected to surveillance. But the situation grew even more explosive when it later became known that the BND had engaged in similar sorts of spying.

"The Germans were running around in outrage mode, but it emerged in 2015 that the Germans were doing the same thing," said Konstantin von Notz, the Greens' intelligence spokesman.

And Deputy Sensburg asked whether the BND had a hand in the alleged tapping of Merkel's phone, which Fritsche vigorously denied. Fritsche added that the chancellor's office would have reacted had the BND expressed concern about the NSA's requests, but that this was not the case.

Sensburg, however, depicted the chancellor's office as ill-prepared to monitor the German intelligence services in an age of rapidly changing technology.

"I would have hoped that you would have expanded your expertise so that you would have understood if someone in the BND had raised the topic," the committee chairman pointed out.

The NSA used specific search terms to gather information on Germans

'Deliberate deception'

With federal elections coming in September, there was more than a whiff of party politics at Monday's sessions. The Social Democrats (SPD) , for example, took the CDU to task for the idea of a "no-spy agreement" with the US, which was floated after the revelations in 2013 but came to nothing.

It was also an election year when Snowden made the spying public. SPD Deputy Christian Flisek accused the Merkel government of creating a smoke screen to deflect attention away from a potentially damaging political scandal. On October 24, 2013, just a month after the CDU won a plurality in elections, Merkel told Germans that "it can't be that friends spy on one another."

Flisek characterized the implied prospect that the United States would be willing to forgo all intelligence operations on Germany as "pulled completely out of thin air" and called it a "deliberate deception of the public."

In 2016, after it had emerged that German intelligence services had also engaged in dubious information-gathering activities, former BND President Gerhard Schindler was sent into early retirement. No official reason was given.

Martina Renner, the Left party's intelligence spokeswoman, pressed Fritsche on why Schindler was forced out, but got no clear answer - other than that she should ask Merkel. Renner promised to do precisely that on Thursday.

Spying target Merkel could also become a political victim

Potential damage

In addition to Fritsche, three representatives of the chancellor's office attended the parliamentary hearing. It was a sign of just how seriously Merkel is taking the potential damage that could be done to her attempt at a fourth term if Germans come to believe that her office knew about the spying but covered it up.

The investigative committee has to file its final report before the end of this legislative period in June. That's ahead of Germany's general election on September 24. The report is likely to be quite unfavorable, and Merkel's government has drawn extremely poor marks in general for its handling of the affair.

On Monday, for example, the influential Süddeutsche Zeitung daily ran a headline reading: "The Government's Balance Sheet on the NSA Scandal Is Shameful."

The committee also questioned the head of the chancellor's office, Peter Altmaier, on Monday evening. Like Fritsche, he took up his current position after the NSA scandal had already broken. He told the committee that the Chancellery had only become aware of the selector list in 2015, following a briefing by Schindler. Altmaier said he knew then that authorities were dealing with "a very serious affair."