RIO DE JANEIRO >> The president of the Brazilian Olympic Committee was arrested today amid an investigation into a vote-buying scheme to bring the Olympics to Rio de Janeiro.

Carlos Nuzman, who is also an honorary International Olympic Committee member, was held for questioning last month by Brazilian and French authorities. They said he was a central figure in channeling at least $2 million to Lamine Diack, a former IOC member from Senegal who helped secure votes when Rio was picked in 2009 by the IOC.

Brazilian authorities have said the behind-the-scenes dealings to win the vote amounted to a “criminal organization,” led by Sergio Cabral, the former governor of Rio de Janeiro who has been jailed on a different corruption conviction.

Securing the games for Rio was just the first step in the massive scheme, according to Nuzman’s arrest order. The Olympics led to massive public investment in infrastructure projects and services contracts, opening a pipeline of money that was used to reward friends and allies and pay bribes.

Authorities said Nuzman would be held because investigators found he tried to hamper the investigation by regularizing assets likely gained with illicit money. About two weeks after being held for questioning, Nuzman amended his tax declaration to add about $600,000 in income, the order said.

“He clearly acted to obstruct the investigation,” said the order, adding that the lack of a clear origin of the extra money “indicated it was illicit.”

Leonardo Gryner, director-general of operations for the organizing committee, was also arrested today.

Investigators said they also recovered a key they believed was for a safe in Switzerland containing gold.

“While Olympic medalists chased their dreams of gold medals, leaders of the Brazilian Olympic Committee stashed their gold in Switzerland,” prosecutor Fabiana Schenider said.

Nuzman’s lawyer, Nelio Machado, told news portal G1 that being detained like this was “harsh and unusual” and denied there had been a vote-buying scheme.

In Nuzman’s last 10 years as Brazilian Olympic Committee president, his net worth increased 457 percent, according to investigators. The 75-year-old Nuzman was one of the most prominent figures in bringing the games to Rio.

Prosecutors previously laid out a scheme in which Nuzman arranged for businessman Arthur Cesar de Menezes Soares Filho’s company to pay Lamine Diack $2 million into an account in the name of Diack’s son, Papa Massata Diack. Today prosecutors said they have since uncovered emails showing the younger Diack asked for more money and received it.

Schenider said she was surprised by the attempts to obstruct the investigation but that the machinations would not thwart justice.

“We are showing that Brazil is no longer a paradise for corrupt people, for thieves,” she said. “We are getting to people who never thought they would have to answer for their actions.”

In a statement, the IOC said it was fully cooperating with the investigation and conducting its own probe.

“Given the new facts, the IOC ethics commission may consider provisional measures while respecting Mr. Nuzman’s right to be heard,” said the statement, which did not offer more details.