"Clearly Snowden is reporting serious crimes that took place on German soil and may even have been directed against people in office," said Peter Gauweiler, parliamentarian for the Christian Social Union, Bavarian sister party to Angela Merkel's Christian Democratic Union.
Speaking to the Süddeutsche Zeitung, Gauweiler said that federal state prosecutors are already obliged to investigate the US spying that Snowden has uncovered, since they are responsible for the protection of state secrets.
"Edward Snowden should be questioned as a witness," he said. "That man has vital evidence."
He said the German judiciary has the power to grant Snowden safe passage if he is being called as a witness, at least for a limited amount of time. This would take the matter out of the hands of the government, which denied the whistleblower political asylum on Tuesday evening.
"Then the case would no longer be in the sphere of politics, but in the cool objectivity of criminal process, being led by what is in Germany an independent judiciary," Gauweiler added.
German state prosecutors have already been investigating the US spy activities since June 27nd. "The federal prosecutor is structuring the observation process from publicly available sources," a federal spokesman said.
Several criminal complaints have already been handed in based on Snowden's revelations.
There is also another way that Snowden, who has been holed up at Moscow airport for a week and a half, could enter Germany legally - should the Bundestag call a parliamentary committee on the spy revelations, it would be able to invite Snowden to appear and testify.
But Gauweiler would prefer the judicial option. "An investigation within the context of a judicial inquiry would be more appropriate than any political action - especially during election campaign times," he said.