CBS

Shortly after Hanssen's arrest, Schiller and Mailer embarked upon a nine-month quest to interview as many of Hanssen's associates, relatives and friends as possible, even interviewing the Hanssen's Opus Dei priest.

Though Mailer and Schiller have different instincts, they've learned how to work together through the years -- and believe that their approaches complement one another. "We're interested in different aspects of (a story), so we have our run-ins as a result," explains Mailer. "But on balance we end up with a fairly rounded portrait of things. We discuss things afterwards and we argue back and forth. I respect Larry's sense of reality -- I think he might respect mine. There are times when we have quite a bit of fun and there are other times when we're ready to punch each other out," he laughed.

For MASTER SPY: THE ROBERT HANNSEN STORY, some of the interviews required them to travel to other countries. Schiller flew to Germany to interview Jack Hoschouer, the man with whom Hanssen had shared his sexual exploits, and Mailer and Schiller went to Russia together to interview members of the KGB that were involved with Hanssen.

Schiller credits some of their past work in Moscow as having helped them to open some doors for this endeavor: "Norman Mailer and I went to Moscow in 1991, and I convinced the KGB to give us the Lee Harvey Oswald files, which became a book called Oswald's Tale, on which I collaborated with Mailer. The way we handled that subject matter earned us a certain respect by the internal security forces of the Soviet Union. So when I went back in 2001 and asked that Viktor Cherkashin and Leonid Vladimirovich Sherbashin, two of the highest ranking KGB officials, grant Mr. Mailer and I interviews, the people who had said no to other well-respected television and print journalists invited Mailer and I to a dinner. We flew to Moscow and we started a series of tape-recorded conversations with Cherkashin and Sherbashin that I think are quite extraordinary. We asked hypothetical questions that were apropos to Hanssen. We discussed what it was like to deal with people that were giving away secrets from their own country, how they would deal with (a mole) when they didn't know who he/she was (as in Hanssen's case), etc. They really gave us an incredible amount of information."

Asked if he was surprised by the access they got with the former KGB officials in Moscow and FBI agents in the U.S., Mailer laughs and says: "Larry has psychic keys that open mysterious doors. How he does it, I don't know sometimes -- but he's very, very good at that. Left on my own I might say okay if denied access, but Larry never gives up."

Per Schiller, "Some of the closest members of (Hanssen's) family visited with Norman and I at Norman's home and at my home, gave us extensive interviews and then introduced us to other members of the family when they felt secure about how we were approaching this. They didn't want their father to be whitewashed. They weren't interested in a pretty picture to counter the image that the United States government was portraying. We told them, 'We want to feel the reality of what your life was like. It's not always going to be the perfect picture.' I think that kind of straightforwardness is what bonded us. They then introduced us to members of Bonnie's family -- her brothers, etc. Before we knew it, the circle of confidentiality grew, and we were able at any time to pick up the phone and ask a technical question. They even arranged for us to be at certain social gatherings so we could see how the family interacted."

As to whether or not Bonnie Hanssen granted them an interview, Schiller responds: "I don't discuss if Bonnie Hanssen cooperated or not because she has kept her privacy, and I respect that privacy. I can only say that the most intimate and closest members of Robert Hanssen's family in one way or another cooperated, not in the making of this film, but in giving us a proper understanding from their point of view."

Per Schiller, details about Hanssen's childhood -- and his challenged relationship with his late father that is featured in this mini-series -- came from his mother and indirectly from Hanssen through his children and others. "I had several telephone conversations with his mother in Florida. And, after his arrest, Hanssen revealed information about his father to several people -- which was then relayed to us. Hanssen's own children were among the people who had heard about it from him when they met with their father in jail, and we talked to them about it. So it was all authenticated from more than one source."

The FBI's Assistance: "The FBI cooperated with the production by not only giving access to Hanssen's former colleagues (such as David Major, who was Hannsen's boss's boss, and Agent Paul Moore, who car-pooled with Hanssen), but by giving access to the agents involved in the case [which included] an anonymous agent who was involved in Hanssen's capture, with whom I spent hours, [and] even FBI agents who worked with Hanssen whom we used as technical advisors." Schiller was, indeed, surprised by their openness with him for this project. "I think they've gotten to a point where they need to acknowledge their mistakes. I think they feel they will be better respected if they're honest."