Almost three years ago, as he waited in his palatial upper East Side penthouse to be sentenced for bilking investors of more than $400 million in a brazen Ponzi scheme, ex-attorney Marc Dreier talked to a former associate in his law firm about his misdeeds.

“Once you make the decision you’re going to do something dishonest, am I so much worse than a shoplifter or somebody that cheats on their tax returns simply because I had the opportunity? You know I don’t really buy into that entirely,” he said. “I think how much you steal is much more a factor of opportunity than by how bad you are.”

He recalled at another point, “The morality of it did bother me, but it didn’t stop me. It’s hard to explain that.”

The interviews of Mr. Dreier by Marc H. Simon, 38, a full-time entertainment lawyer and part-time documentary maker who had worked in Mr. Dreier’s firm, are at the core of “Unraveled,” a film Mr. Simon produced and directed that is being released April 13 at the Village East Cinema in New York, in Los Angeles and perhaps in Washington, D.C. Mr. Simon said the 85-minute film would be shown on cable systems’ video-on-demand channels.

Visit the film’s official website and see the trailer.

Mr. Simon estimated that he filmed Mr. Dreier for 40 to 50 hours in the two months before Mr. Dreier was sentenced in July 2009 to 20 years in a Minnesota prison.

The film will provide no solace to Mr. Dreier’s creditors, who are still seeking relief through his law firm’s bankruptcy.

“I think the concern is that the movie will seek to justify or explain his actions as anything other than a sociopathic and morally bankrupt [individual],” said Jerrold Bregman of Curtis, Mallet-Prevost, Colt & Mosle.

Mr. Bregman is representing his partner, Steven Reisman, who is pursuing claims on behalf of the creditors of 360networks, a telecommunications company.

Mr. Dreier’s firm represented the unsecured creditors committee in the bankruptcy of 360networks, the largest client victim of Mr. Dreier’s fraud based on the $50 million Mr. Bregman said Mr. Dreier stole.

The documentary has already been shown at about a dozen film festivals. In it, Mr. Dreier gives similar explanations for his conduct as he gave in late 2009 to “60 Minutes” and Vanity Fair magazine.

Mr. Simon said he believes Mr. Dreier, now 61, who has not seen the film, is “intellectually remorseful” but not “emotionally connected to the damage he caused.”

Mr. Simon is a partner at Cowan, DeBaets, Abrahams & Sheppard in New York, where he represents film and TV companies, producers, directors, writers and talent. He was involved in business negotiations for the films “Winter’s Bone” and “The Kids Are All Right.”

“Unraveled” is his third film. He wrote and produced “After Innocence,” a well-reviewed 2005 film examining the lives of wrongly convicted defendants after they have been exonerated. And he directed and produced “Nursery University,” which portrays parents’ efforts to get their children into “feeder schools” that lead to admission to prestigious universities.

Mr. Simon was almost done with “Nursery University” when the idea for a film about Mr. Dreier was brought to him by a client, Stick Figure Productions, but he initially shunned the idea.

The collapse of Mr. Dreier’s firm was a “personal tragedy” for him, he said. Mr. Simon had worked at the firm for six years, and Mr. Dreier had been a mentor who supported Mr. Simon in growing his entertainment law practice, he said.

Moreover, Mr. Simon said he took a “significant financial impact” when the nondiscretionary bonuses he was guaranteed did not materialize. He declined to specify the exact amount.

But Mr. Simon said he eventually decided that he was in a unique position as a lawyer of Mr. Dreier’s former firm and a director to tell the story, and he went ahead in partnership with Stick Figure.

Ambush Entertainment, an independent film production company based in Los Angeles, partially financed the film, along with a presale to Showtime Networks, Mr. Simon said. He would not disclose how much the movie cost to produce.

Mr. Simon said the filmmakers paid an “access fee” of “up to around” $50,000 to the private security company that provided guards who monitored Mr. Dreier while he was under house arrest before his sentencing.

Mr. Simon added that none of the film’s proceeds are going to Mr. Dreier.

Mr. Simon said he believed Mr. Dreier trusted him to be fair and that Mr. Dreier thought the film was an opportunity to show that he was not a bad person, but someone who made bad decisions. Mr. Dreier used the production team as a sounding board for his arguments, Mr. Simon said.

Finally, Mr. Simon said, Mr. Dreier just may feed off attention.

Lacking ‘Moral Grounding’

Woven throughout the film are clips of Mr. Dreier’s daily life under house arrest, images of his earlier life and scenes of media coverage. But “Unraveled” is dominated by Mr. Dreier’s comments on how his life and career did just that—unraveled.

Rationalizing his behavior, Mr. Dreier says, “I was going through a divorce. I felt very, very isolated. I really didn’t have any relationship with anybody, personal or professional, that…could sort of give me moral grounding.”

Mr. Dreier and his wife separated in 2003, according to court papers. The film says the fraud started in 2002.

Mr. Dreier also says he was not satisfied with his career.

“I spent 20 years sort of as a lawyer at a large firm, for the most part, pushing around paper. That wasn’t very gratifying,” he says. “You’re not getting paid as well as most clients and you feel that you’re working very hard and you’re not achieving the level of financial success that you deserve.”

Mr. Dreier explains that he needed more funding for the growth of his 250-attorney firm, but he did not have the credit to borrow money.

“So I guess the idea occurred to me that I would try to borrow money with somebody else’s credit,” he said.

That somebody was real estate mogul Sheldon Solow, whom Mr. Dreier had represented in a number of cases. Part of Mr. Dreier’s scheme involved assuming the identity of Solow Realty & Development Co. to market phony promissory notes in the company’s name to hedge funds.

Mr. Dreier previously had been ordered to pay about $300,000 in sanctions in one of his cases with Solow. In the film, he complains that Mr. Solow did not come to his defense, foot the bill for the sanctions or help in rehabilitating his name.

“I guess what I resented most is that he absolutely didn’t seem to care,” Mr. Dreier says.

Messages left at Mr. Solow’s office for comment were not returned.

Mr. Dreier became more brazen, even as the firm was draining off more money than he anticipated and the debt mounted.

“The domino effect was that I had to keep borrowing new money to pay off old money. Every week for years, I was involved in this process of updating, inventing, sustaining the financial statements,” he says. “I was getting inquiries from a dozen different sources.”

In the movie, Mr. Dreier refuses to answer questions about his family’s reaction to his crimes, in particular his mother, who was in her mid-80s at the time of filming.

“She’s been hurt by this,” he says, his eyes moistening in his only emotional moment of the film.

Other than Mr. Dreier, only his son Spencer gives his opinion in the film, commenting briefly that his father was wrong and “the means don’t justify the ends.”

Mr. Simon said the absence of interviews with victims and creditors was a “practical and creative decision.”

He said he knew directors of hedge funds, many of Mr. Dreier’s victims, would have no interest in being filmed, while lawyers at the defunct law firm wanted to move away from the incident.

The film lets Mr. Dreier tell his version of events while allowing the audience to decide whether he has remorse, Mr. Simon said.

‘Interesting Human Story’

Gerald Shargel, Mr. Dreier’s lawyer, who appears in the movie advising his client but is not interviewed, said there are no pending legal matters in Mr. Dreier’s criminal case.

“He’s admitted his guilt in the courtroom, and he’s admitted his guilt publicly,” he said. “There’s no way” the film “would affect any future litigation, real or contemplated.”

A film crew shoots Marc Dreier at his Upper East Side penthouse.

Mr. Shargel said his client’s participation in the film “was a catharsis,” for Mr. Dreier. “He was reflecting on his life and reflecting on his criminal acts, and I think he wanted to give an unvarnished account of what occurred.”

The attorney added that he has stayed in touch with Mr. Dreier.

“He’s doing as well as can be expected under the circumstances,” Mr. Shargel said.

The movie ends with Mr. Dreier’s sentencing.

“As much as Dreier wants to put his spin and or rationalization on his actions, when an individual such as Dreier crosses the line, he is held accountable and ultimately silenced by the judicial system. The arc of the film is a countdown to the sentencing order,” Mr. Simon said in an e-mail. “That’s the proper ending.”

Bankruptcy Trustee Sheila Gowan, who is charged with liquidating Dreier LLP, said she has seen the film and thinks “it’s a very interesting human story” but does not believe it will influence the bankruptcy proceedings.

Sean Southard, the lawyer for the creditors committee in the firm’s bankruptcy, said that of the more than $500 million in total claims from creditors, nothing has been paid out to the vast majority.

“I would say the passage of time has dulled the emotion that surrounded it,” he said. “Most folks have attempted to move on but when the circumstances surrounding the fraud are discussed and thought about, it certainly renews the emotion and the anger.”

He added, “From what I have heard about Mr. Dreier, he liked the spotlight, liked the attention in his former life and it’s not surprising that he might seek that attention now while incarcerated in Minnesota. I suspect he’s craving that attention.”

Mr. Simon said that Mr. Dreier is representative of numerous white-collar criminals like fellow Ponzi schemers Bernard Madoff and Allen Stanford “who have been exposed in the current era of financial and corporate crime.”

“The film is a microcosm of all that we’ve seen. He is representative of these times, and I think that’s the value of this film,” he said.