DW: A 31-year-old employee of Germany's foreign intelligence agency is accused of having spied on behalf of the United States. Is that everyday business for secret services, or is it a huge scandal?

Erich Schmidt-Eenboom: It's a huge scandal. We're already in the situation that Germany's foreign intelligence agency (BND) doesn't regard American agents in Germany as hostile forces - they are allowed a lot in terms of espionage in Germany - but that a BND employee would be sent to spy on a constitutional body is an outrageous transgression of intelligence cooperation and its boundaries.

Should this suspicion prove to be true, what kind of consequences would that spell for German-US relations?

This would strain the political sphere, for sure. But in terms of secret services I would expect a more professional way of thinking, meaning: Intelligence services behave in a certain way; so after some disgruntlement, one proceeds with business as usual.

The employee was said to be sent specifically to cover the investigative committee that is conducting an inquiry into NSA surveillance. What sort of information could be of interest to the US?

There's a whole array of information [that could be interesting]. For one, they want to make sure that they know everything that [Edward] Snowden tells the committee - even in secret meetings.

Then of course they want to know to what extent the BND informed parliamentarians about cooperation between BND and NSA, which is classified as secret. Overall it's about researching the extent of committee's knowledge so that one can prepare adequately for a final media response.

Is this incident going to influence the committee's work?

The committee was most likely not caught off guard. It always had to assume that many foreign secret services - not just the US - were interested in its work. It would be wise to ban all authorities, which already have too much influence on these committees as it is, at least from closed sessions.

Initially it had been suspected that this employee was spying for the Russians. That still seems not completely off the table. Do you think it's possible that said employee tried to plant a red herring to make it look like he was working for the NSA while he was interrogated?

I don't think so, because it is indeed possible to check that. In the intelligence business, it is possible to be recruited under false pretences. Meaning he could have been told he was working for an American agency by people actually working for Russian intelligence. That's indeed possible in this business.

How does the BND recruit its employees? Is it through an ordinary application process, or different?

By now it's an ordinary application process. Jobs are posted, there are applicants, and these applicants are of course scrutinized - both before they are employed, and then afterwards on a regular basis. That's done to also make sure that they are not working for foreign agencies.

What sort of mechanisms are in place for the agency to observe it's own employees?

You look at behavioral problems such as alcohol abuse, compulsive gambling, excessive debt; you check family relations in critical states, examine a person's character, a person's development, and ask for references in order to get a complete view of the person and not just their apparent achievements.

What punishment awaits a spy who has been uncovered in Germany?

It depends on the type of foreign agent activity. Since we are dealing here with the case of spying on a constitutional body, I expect a high punishment of several years imprisonment without parole [if found guilty].

Is this an isolated case, or have incidents like this happened often in the past?

Americans have always spied on German politics, military and society. But this hasn't been prosecuted, it's simply been put up with. There have also always been cases where BND [employees] have leaked information to American intelligence.

But we have never had such a serious case, of a German secret service employee spying on a constitutional body for Americans.

Erich Schmidt-Eenboom is a well-known secret service expert and has published numerous books and articles on that matter. He is head of the Research Institute for Peace Policy in Bavaria.