The recent arrest in Spain of two brothers accused of passing off forged paintings as the work of America’s greatest Modernist masters has refocused attention on the people behind an art fraud that has lasted 15 years, garnered $80 million and helped bring down New York’s oldest gallery, Knoedler & Company.  But court documents filed in connection with the case reveal that ambitious art swindles like this one depend on far more than an ingenious con operation or a gifted imitator. Rather, a network of people, sometimes unwittingly, repeatedly helped lend these fake paintings a veneer of credibility. When it comes to the sale of bogus art, it takes a village.  Some art experts who authenticated counterfeits said to be by Jackson Pollock, Mark Rothko and Robert Motherwell were paid undisclosed consulting fees by Knoedler. Other scholars privately identified several works as fake, but were instructed by lawyers to stay quiet to avoid being sued. And the industry’s ubiquitous lack of transparency prevented anyone from discerning a pattern — even after some forgeries were identified.  These problems have permeated the industry for decades, said Stephen Urice, a professor at the University of Miami School of Law. He pointed to a 1978 court ruling: “In the fantasy land of marketing in the fine arts,” prestigious names are “dropped freely as rain,” and large sums quickly change hands, Judge J. Shorter of New York State Supreme Court wrote. “In an industry whose transactions cry out for verification of both title to and authenticity of subject matter, it is deemed poor practice to probe into either.”  In the Knoedler case, the only person convicted so far is Glafira Rosales, a Long Island dealer who pleaded guilty to fraud last fall. Prosecutors say her co-conspirators included her boyfriend, Jose Carlos Bergantiños Diaz; his brother, Jesus Angel Bergantiños Diaz; and Pei-Shen Qian, the artist who forged the works. The Bergantiñoses have been released on bail in Spain, while Mr. Qian is in China. The dealers who sold dozens of these works — Ann Freedman, the former president of Knoedler, and Julian Weissman — have repeatedly said that despite the lack of documentation, they were convinced the art was genuine.  Jack Flam, an art historian who was one of the first to challenge the authenticity of the Rosales paintings, said: “If you asked me what the biggest factors were behind this thing succeeding so long, first is that everybody was afraid to be sued. People give credibility to works unwittingly by keeping quiet.”  Mr. Flam is the president of the Dedalus Foundation, a nonprofit group created by the painter Robert Motherwell. He and his colleagues were initially impressed by the supposed Motherwells, but by late 2007, as the number of new discoveries attributed to Motherwell grew, they became uneasy. Mr. Flam began making inquiries and soon discovered that the Richard Diebenkorn estate, the Willem de Kooning Foundation and the Barnett Newman Foundation were also suspicious of works that Knoedler was selling.  “The foundations all knew that something was wrong with their particular artist but didn’t know anybody else had problems,” Mr. Flam said. “I was the first one who went around and starting asking everyone.”  Indeed, as early as 2005, Eugene Victor Thaw, a leading expert on Jackson Pollock, said he doubted the authenticity of two Rosales Pollocks that Knoedler was selling. Although he later privately shared his suspicions with a handful of people, Mr. Thaw had stopped formally giving opinions years before in the wake of several lawsuits.  And in June 2008, months after Dedalus started asking questions, three Barnett Newman experts — John O’Neill, Carol Mancusi-Ungaro and Yves-Alain Bois — concurred that what was said to be a Newman, from Knoedler, hanging at the Beyeler Foundation in Switzerland was a fake. But as Mr. Bois wrote in an email to the Beyeler, he and his colleagues were “told not to make a public announcement” by a lawyer for the Barnett Newman Foundation, who feared a lawsuit.  Exhibitions at a prestigious museum like the Beyeler can bolster a work’s value and provenance, and Ms. Freedman had previously arranged to display two other paintings provided by Ms. Rosales — both attributed to Rothko — at the Swiss foundation’s gallery. As for the Rosales Newman there, Oliver Wick, a Beyeler curator, had been trying to sell it to a German museum for $18 million on Knoedler’s behalf, according to internal gallery documents.  Mr. Bois’s email, however, spurred two other Beyeler curators, Philippe Buttner and Ulf Küster, to take down the questionable Newman. Mr. Küster told Mr. Buttner in an email: “I had a similar problem with an offer of a Pollock from Knoedler.”  Still, none of these experts made public their doubts about these or any other works coming from Knoedler. A month later, in July 2008, Ms. Freedman sold another Rosales fake — this one attributed to Franz Kline — for $3.375 million.  Keeping quiet is standard practice. The College Art Association, whose members are art professionals, recommends that art historians give their opinion “only when there is a written request by the owner of the work,” and then only if the owner promises to indemnify the scholar against legal damages. Museums, which once routinely gave opinions on works, have also stopped offering assessments.  An expert’s silence or a refusal to offer any opinion can be interpreted in different ways, however. Ms. Freedman testified in court that she frequently assumed that the absence of expressed doubt meant that an expert was affirming a work’s bona fides.  In March the New York State Legislature took a step toward easing the scholar’s dilemma by introducing a bill that would protect art experts who offer opinions on a work’s authenticity from “frivolous” lawsuits.  There were scholars who declared that the Rosales works were genuine. Some were paid fees for their time or earned commissions. In April 2008, for example, Mr. Wick, the Beyeler curator, sold a Rosales Rothko on Knoedler’s behalf for $7.2 million and vouched for its authenticity. He ended up earning $450,000 in fees from the sale: a $300,000 “consultant’s fee” from Knoedler, according to an internal gallery invoice, and a $150,000 commission from the buyer. In a complaint filed last month in Manhattan federal court, the buyer says Mr. Wick did not reveal his financial ties to Knoedler. Mr. Wick tried to sell a Rosales Rothko twice more, in October 2008 and in March 2009, the complaint says.  Mr. Wick, who left Beyeler last year to join the Kunsthalle Zurich, resigned his curator post there this month. A Kunsthalle spokeswoman said his leaving the museum had nothing to do with the lawsuit. Mr. Wick could not be reached for comment.  Art experts who were consulted by Knoedler emphasized that they were not paid for their opinions on a work’s authenticity. But they were sometimes paid for other efforts, such as research or writing. The art historian E. A. Carmean Jr., who authenticated some of the Rosales works, for example, was hired by Knoedler to try to document the works’ provenance.  David Anfam, an art historian and a senior consulting curator at the Clyfford Still Museum in Denver, tried to persuade skeptics that works sold by Knoedler from Ms. Rosales were authentic. According to email exchanges, he followed up with requests for compensation for his time. A day after assuring a colleague about the paintings, for example, he wrote to Ms. Freedman’s assistant: “In all fairness, I think Ann should soon start thinking” about “some measure of recompense for my endeavors.”  Mr. Anfam said that while he did raise the idea of compensation for his expertise and research, he never received any payments from Knoedler.  The art industry’s tradition of secrecy can also mask warning signs. Ms. Rosales did not raise suspicions when she insisted that the owner of the supposed masterworks —called Mr. X — demanded anonymity. And the use of the common catchall phrase “private collection” meant that no one besides the dealers knew these works were provided by a single source. So when the Kemper Museum of Contemporary Art in Kansas City, Mo., for instance, learned in 2006 that an ostensible Richard Diebenkorn work sold by Knoedler was counterfeit, the museum did not realize that it might be linked to a larger forgery scheme.  “Secrecy is something that occurs left and right in this business,” Mr. Weissman explained in a deposition. “Things just simply say, ‘Collection of the artist,’ or ‘By the artist, private collection,’ and they get sold all the time.”  Even now, some owners of paintings handled by Ms. Rosales may be unaware that they purchased forgeries, because Knoedler and Mr. Weissman sometimes sold works through other galleries.  A version of this article appears in print on May 3, 2014, on page C1 of the New York edition with the headline: Selling a Fake Painting Takes More Than a Good Artist. Order Reprints|Today's Paper|Subscribe
A wide network of professionals and industry practices help conspirators coat fake works with a veneer of credibility.