SPIEGEL: Mr. Schwan, you spent eight years working with former German Chancellor Helmut Kohl on his memoirs. During this period you had complete access to all his documents and you recorded 630 hours of interviews. How much material do you have at your disposal today?
Schwan: I took a lot of notes and made quite a few copies. And of course I made private copies for myself of the conversations I had with Helmut Kohl, in addition to the 105 days we spent together when I had the tape recorder running all the time. I used 10 percent of this material in the memoirs, so 90 percent of it remains unpublished.
SPIEGEL: What do you plan to do with this material?
Schwan: We need to bear in mind that audio recordings of Helmut Kohl have become more valuable in the wake of his fall in 2008. His ability to communicate in depth has been impaired by the fact he has difficulty speaking. As we know, Hans-Peter Schwarz, who wrote a recently published biography of Helmut Kohl, only met him twice -- in February and in the autumn of 2011. So what I have is a unique treasure trove and I am enormously proud of it. One day I will bring this treasure to light.
SPIEGEL: Are you considering publishing it?
Schwan: I'll be publishing a new biography to mark Helmut Kohl's 90th birthday. The focus will be on new revelations. To some extent, it will be my interpretation of what I gleaned from eight years of collaboration with Helmut Kohl, during which time I was granted access to all his files. You can imagine what bringing to light documents that have been off-limits to the public for 30 years means to a journalist and historian.
SPIEGEL: What do you mean by "interpretation?"
Schwan: People are always talking about Helmut Kohl, his legacy, his era, and making statements that he is no longer in a position to refute. I feel it is important to do the man justice. I object to the way people these days can get away with misrepresenting things because he's no longer able to contradict them. I know what his weaknesses are, but I was always aware that his priority was not just to be proved right with hindsight, as so many people suggest.
SPIEGEL: You enjoyed a privileged status in the Kohl family home. What exactly was the arrangement? Did you have to sign a contract guaranteeing secrecy?
Schwan: No, I would never have signed a contract like that. Now and then Helmut Kohl would say "we can't write that now" or "you can only write that after my death," but that was all.
SPIEGEL: The former chancellor trusted you more than anyone else. You were even permitted to look at his Stasi file (kept by the former East German secret police). Is he aware that you are now planning to use the material for your own purposes?
Schwan: He might read about it in SPIEGEL even though he maintains he doesn't read it. But the new woman at his side, Maike Kohl-Richter, will be on her guard and might possibly call in the lawyers.
SPIEGEL: Were any attempts made to claim back the material you had acquired?
Schwan: When we went our separate ways, the former chancellor had his lawyers try to recover documents I had in my possession. But I made it very clear: These are my own notes, it's my own work. They can't take it away from me and they would have no legal basis for doing so.
SPIEGEL: The family felt you breached their trust with your biography of the former chancellor's first wife, Hannelore Kohl, published in 2011. Another book would undoubtedly be an even more serious breach of trust.
Schwan: I don't think so. Helmut Kohl often said to me, "You can publish that when I'm dead." I'm sure I have that on tape somewhere. If he had a chance to talk to me alone for five minutes, I would regain his trust immediately. He would say: Write what is intellectually honest, as you always have, without any ideological slant or prejudice.
SPIEGEL: So you're not worried about a court case? Your book about Hannelore Kohl sparked a legal battle with her sons that is still ongoing. He himself also briefly considered taking legal steps against you.
Schwan: I have no doubt that Helmut Kohl sees my book about Hannelore Kohl as a wonderful tribute to the achievements of his first wife. If he could still express himself, that's what he would say. His sole criticism would be of the final chapter. In his opinion I should have left out all mention of what his wife saw as his infidelity. But the fact remains: What I wrote was not untrue.
SPIEGEL: Your collaboration ended in spring 2009. Have you been in touch with the former chancellor since then?
Schwan: No, unfortunately not. Although I have never actually tried to get in touch. No one can get close to him any more. Everything has to go though his Berlin office, it's a very complicated process.
SPIEGEL: So you never attempted to complete the fourth volume of his memoirs?
Schwan: I couldn't understand why Helmut Kohl allowed work on the fourth volume to be stopped. I had already written half of it when he ended our collaboration. I'm convinced that his new wife was behind this decision. I don't know exactly what the state of Helmut Kohl's health is but I've heard that his mental faculties are fine. If this is true, then I'm personally deeply disappointed by this man who trusted me completely for so long and who also profited from me considerably. I cannot understand why our relationship has been ruined and it pains me that it has.