BERLIN — When a wealthy married couple bought the Berliner Zeitung, a distinguished but ailing survivor of the East German press, they timed their newspaper’s big revamp for the 30th anniversary of the fall of the Berlin Wall last month.

In an attention-grabbing two-page editorial, the entrepreneurial couple, Silke and Holger Friedrich, urged a reimagining of history since German reunification. They argued that 30 years after the wall came down, East Germans should wrest back control of their own narrative from the West, and stirred controversy by defending the last East German leader.

But there was an essential piece of information that they left out.

A week later, a rival newspaper reported that Mr. Friedrich, 53, had been an informant for the Stasi, the feared secret police of Communist East Germany in the late 1980s.

Instead of apologizing, Mr. Friedrich chose to come out fighting.

He argued that he was coerced into being an informant and that he worked with his supposed victims to ensure that he disclosed little of value. He insisted that he has little, if anything, to be sorry for. But at the same time, he acknowledged that he could not be sure whether anyone was harmed as a result of his actions.