NEW YORK (AP) — A Russian billionaire who accused Sotheby’s of teaming up with a Swiss art dealer to cheat him out of tens of millions of dollars became tearful Friday while testifying about discovering he’d been part of a con game too common in an “art market that needs to be more transparent.”

The emotional moment came as fertilizer magnate Dmitry Rybolovlev, speaking through an interpreter, completed two days of testimony in Manhattan federal court to support his lawsuit against Sotheby’s.

Once worth at least $7 billion, Rybolovlev said he trusted his dealer, Yves Bouvier.

“So when you trust people, and I’m not a person who trusts easily, but when a person is like a member of your family,” Rybolovlev said as he dropped his head briefly before wiping tears from his eyes and continuing on: “There is a point in time and that you start to completely and utterly trust a person.”

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Rybolovlev is trying to hold Sotheby’s responsible for what his lawyers said was the loss of over $160 million. His legal team said Bouvier pocketed the sum by buying famous artworks from Sotheby’s before selling them to Rybolovlev at marked up prices. In all, Rybolovlev spent about $2 billion on art from 2002 to 2014 as he built a world-class art collection.

On cross examination, a Sotheby’s lawyer got Rybolovlev to admit that he trusted his advisers and didn’t insist on seeing documents that might have shown exactly where his money was going, even when he bought art sometimes worth tens of millions of dollars.

In his testimony, Rybolovlev blamed murky practices in the blue-chip art world for leaving him damaged financially.

“Because when the largest company in this industry with such a profound reputation does these actions, it makes it incredibly difficult for clients like me that have experience in business to know what’s going on,” he said, supporting his lawyers’ arguments that Sotheby’s either knew — or should have known that Rybolovlev was getting cheated and notified him.

When asked by his lawyer why he sued Sotheby’s, Rybolovlev said: “So it’s not an issue of money. Well, not only of money. It’s important for the art market to be more transparent. Because ... when the largest company in this industry is involved in actions of this sort, you know, clients don’t stand a chance.”

In an opening statement earlier in the week, Sotheby’s attorney Sara Shudofsky said Rybolovlev was “trying to make an innocent party pay for what somebody else did to him.”

Rybolovlev’s lawyer, Daniel Kornstein, said in his opening that Sotheby’s joined an elaborate fraud.

“Sotheby’s had choices, but they chose greed,” he said.

Rybolovlev claims he was purposefully deceived by Bouvier and a London-based executive at Sotheby’s as he bought 38 art pieces.

Only four are at issue in the trial, including Leonardo da Vinci’s “Salvator Mundi, ” Latin for “Savior of the World,” which Rybolovlev’s lawyers say Bouvier bought from Sotheby’s for $83 million, only to resell to Rybolovlev a day later for over $127 million. In 2017, Rybolovlev sold it through Christie’s for a historic $450 million as it became the most expensive painting ever sold at auction.

In December, Bouvier’s lawyers announced that Bouvier had settled with Rybolovlev under undisclosed terms that ensure neither will comment on their past disputes.

Bouvier’s Swiss lawyers, David Bitton and Yves Klein, said earlier this week that Bouvier “strongly objects to any allegation of fraud.”

They said the allegations against Bouvier in New York have been rejected “by authorities around the world,” with all nine legal cases brought against him in Singapore, Hong Kong, New York, Monaco and Geneva, Switzerland, being discontinued.

In 2018, Rybolovlev was included on a list that the Trump administration released of 114 Russian politicians and oligarchs it said were linked to Russian President Vladimir Putin.

However, he was not included on a list of Russian oligarchs sanctioned after Russia attacked Ukraine, and Kornstein told jurors that his client, who studied medicine and became a cardiologist before switching to business, hasn’t lived in Russia in 30 years.