MIAMI (AP) — The son-in-law of a prominent Venezuelan opposition leader has pleaded guilty to money laundering charges for his role in a vast bribery conspiracy to siphon $1.2 billion from the state-owned oil company.

As part of his plea agreement announced Tuesday in federal court in Miami, Fernando Vuteff admitted to earning at least $4.1 million from a Spanish real estate company and financial institutions in Europe and Malta used to launder money on behalf of several Venezuelan government insiders.

Brian H. Bieber, an attorney for Vuteff, told The Associated Press that his client “accepted full responsibility for his conduct and the role he played in this case” but declined to comment further.

The Argentine-born asset manager is the latest caught up in a multiyear investigation, known as Operation Money Flight, targeting corruption inside Venezuela’s oil industry, the source of virtually all the OPEC nation’s export earnings.

Starting in 2006 until around 2018, Vuteff, who is the son-in-law of former Caracas Mayor Antonio Ledezma, worked with a Swiss banker to recruit wealthy South American clients to offshore accounts in European banks. Among their clients was Raul Gorrin, a powerful media tycoon described in the plea agreement as a “billionaire businessman who was the owner of a Venezuelan television network.”

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Gorrin was charged separately in 2018 for his role in the alleged conspiracy. According to investigators, the conspirators ginned up a currency-exchange scheme using fake loan agreements with the oil giant PDVSA designed to embezzle between $600 million and $1.2 billion at a time of collapsing production levels.

To facilitate the dirty dealmaking, the conspirators paid out millions in bribes, including to family members of one unnamed official identified in Vuteff’s plea agreement as “Los Chamos” — Venezuelan slang for “the kids.” The “Chamos” are President Nicolas Maduro’s stepsons, two Americans previously told the AP, speaking on the condition of anonymity because of the sensitive nature of the allegations.

Vuteff plowed his personal take from the conspiracy into real estate in Miami, Madrid and the capital of Paraguay, as well as a bank account belonging to a shell company in the Caribbean island of Turks and Caicos, according to the plea agreement.

Corruption is rampant in Venezuela — the country trails only Somalia in a widely cited ranking of 180 countries for perceived levels of graft — and U.S. prosecutors have uncovered billions in fraud and bribes at PDVSA in recent years.

But the Miami probe — the biggest money-laundering case ever lodged against Venezuelan officials and their associates — has slowed of late as several key prosecutors have resigned, the Justice Department has turned its attention to national security probes in China and Russia, and the Biden administration has sought to entice Maduro into allowing free and fair elections.

Vuteff’s father-in-law, Ledezma, was for years one of Maduro’s fiercest opponents, leading massive protests against the self styled socialist leader, before he was arrested in 2015 on allegations he was plotting a coup. He fled house arrest in 2017 and took up residency in Spain.

Ledezma, in a statement, said that he was focusing on providing support for his daughter and grandchildren and didn’t comment on Vuteff’s crimes.

“I do not interfere in a process that depends on the judicial administration of a democratic country, whose verdicts must be respected,” he said.