Diana B. Henriques prepared to work with Robert De Niro the only way she knew: She asked questions.

Henriques, who covered Wall Street for the Inquirer for several years in the 1980s, was a New York Times reporter when in 2011 she became the first journalist to get a jailhouse interview with Ponzi schemer Bernard L. Madoff,  She plays herself in The Wizard of Lies, an HBO movie premiering Saturday that's based on her best-selling book about the Madoff scandal.

"Well, you know, Oscar Wilde said you should always [be] yourself, because all the other roles are taken," Henriques said after an HBO news conference in January to promote the project. "I had to audition. I had to pass a screen test. So it was remarkable. But I wasn't really playing anybody. I was just being a reporter."

Directed by Barry Levinson, The Wizard of Lies stars De Niro as Madoff and Michelle Pfeiffer as his wife, Ruth. The film uses Henriques' Madoff interview as a framing device for the story of the scandal and her distinctive voice as occasional narration.

The voice-over aspect felt familiar, Henriques said. After a "debilitating" carpal-tunnel injury in 1997, she started using voice-recognition software to dictate her stories and books. (Her fifth book, A First-Class Catastrophe: The Road to Black Monday, the Worst Day in Wall Street History, will be published in September.)

"It was like reading the book, really," she said. "The opening is almost directly out of the prologue."

As for her scenes with De Niro, "those interviews with Madoff in prison are just etched on my mind. I mean, that was one of my most remarkable experiences as a reporter. No tape recorder. No video. Old-fashioned notebook and pen, that's all I had. So it felt very much like something I'd done before. It wasn't an unusual experience to be interviewing Bernie Madoff."

What was different: "The environment, all of the artistry around it, the cinematographer and the lighting and the makeup, all of that. … I was like a kid in a candy store, I tell you."

Although she has worked with great writers, editors, and photographers, she said, "there are forms of artistry involved in the making of a film that I'd never been exposed to before. I get goosebumps now just talking about it."

"THE WIZARD OF LIES": Robert De Niro portrays Bernie Madoff and Michelle Pfeiffer plays Ruth Madoff, his wife.
"THE WIZARD OF LIES": Robert De Niro portrays Bernie Madoff and Michelle Pfeiffer plays Ruth Madoff, his wife.

But Henriques wasn't so swept away that she didn't speak up when she thought something wasn't right.

"The initial scene that they had written for me to interview Bernie I felt was too combative. It was too confrontational. No reporter doing that initial interview, where you're trying to warm him up," would behave that way, she said.

"I worked 18 months to get him to talk to me," she said. "I'm not going to walk in there and say, you know, 'OK, come clean here, guy.'

"So I said, 'I think you need to dial these questions back a little bit.' That was the scene they used for my screen test, and I did it as written first time round.  And then I said, 'You know, I'm just not comfortable with how these questions are framed. They should be a little bit more cordial, a little bit more friendly.'

"And Barry [Levinson], who was there for the screen test, he said, 'Well, fine. Just put them in your own words.' And I did, and the script adapted to the way a real journalist would work. So just looking at that tiny piece of the movie, about how a journalist does her craft, I couldn't be more pleased."

Asked at the news conference about working with De Niro, she described him as "a vacuum cleaner" in his preparation.

"By the time we actually wound up on the set, he had just about learned everything I could possibly tell him about Bernie. But even through that filming, there would be moments where he would say, 'Is this right with the hands?' That kind of thing, down to excruciating details. It was really an unforgettable experience to see Robert De Niro so totally occupy that character," she said.

"At one point, Barry had the brilliant idea of having Bob and me improvise questions and answers for what seemed to go on for hours and hours, but I think it was just 10 or 12 minutes, and you'll see some pieces of that in the film," she said.

"This was not real hard for me. I'm a journalist asking questions. But Bob is having to answer those questions extemporaneously out of Bernie Madoff's brain. And I made the vow right then and there to never take investment advice from Bob De Niro, just in case he's channeling his inner Bernie. It was so convincing."

De Niro, asked at the news conference whether he considered Madoff a sociopath, said: "The only thing that I feel is that his kids didn't know, and his wife didn't know. What he did is beyond my comprehension. So there's a disconnect somehow in him, and I still would like to understand."

Henriques suggested labels might not matter when it comes to Madoff.

"What you need to understand and what I think you'll see in Bob's performance is how plausible con men like this are, how utterly they can seize your trust and your imagination and make you believe. A friend of mine once said, 'The thing about a Ponzi schemer is they can do a perfect impersonation of an honest man.' … What it boils down to is how he treated people and how incredibly magnetic he was."