Democratic senators are questioning why the Justice Department moved to drop fraud charges against billionaire Indian businessman Gautam Adani, a significant reversal in a high-profile case.

Elizabeth Warren of Massachusetts and Richard Blumenthal of Connecticut wrote a letter asking acting Attorney General Todd Blanche about the “reportedly ‘transactional nature’” of the decision to forgo the case.

Adani, who is estimated to be worth more than $100 billion and was considered the richest person in India, was indicted in 2024 in the Eastern District of New York over his suspected role in a massive fraud and bribery scheme, in which he is accused of defrauding U.S. investors and paying off Indian government officials to win a bid to develop the country’s largest solar power plant. He called the accusations baseless.

Trent McCotter, the principal associate deputy attorney general, and U.S. Attorney Joseph Nocella told U.S. District Judge Nicholas Garaufis in a court filing last month that the office wouldn’t “devote further resources” to the case.

The filing didn’t include signatures from the prosecutors assigned to the case, which would be customary.

Garaufis hasn’t yet signed off on the request.

According to Warren and Blumenthal, the Justice Department backed off after Adani hired Robert Giuffra, one of President Donald Trump’s personal attorneys. The senators want to know whether Adani, 63, promised to invest $10 billion in the U.S. if the charges were dropped.

“The DOJ’s decision gives the appearance that Mr. Adani — with the help of one of the president’s personal lawyers — bought his way to criminal immunity, trading the promise of an investment in the United States for immunity from an alleged multi-billion dollar bribery scheme,” the senators said.

The Justice Department and the U.S. attorney’s office in Brooklyn didn’t immediately respond to requests for comment. Neither did Adani’s attorney.

The senators said reports of an offer raised “serious questions about corruption under President Trump and about the role that Mr. Adani’s politically salient offer played in the DOJ’s decision.”

“The DOJ also risks furthering the misperception that bribery pays in the long run,” they wrote.

They also want to know whether there was communication between the White House and the Justice Department over the case.

Republicans control Congress, so it’s unlikely the Justice Department will be pushed to respond to the letter. The senators asked for answers no later than June 25.

Adani, 63, founder and chairman of the Indian conglomerate Adani Group, was among multiple defendants in the 2024 case.

Federal prosecutors argued that he and others paid $250 million in bribes to Indian government officials so Adani Green Energy, a subsidiary of Adani Group, would win approval to develop India’s largest solar power plant. The contracts were projected to generate $2 billion in profits over 20 years, according to the indictment.

Federal prosecutors also alleged that the defendants swindled U.S. and international investors by procuring funds “on the basis of false and misleading statements.”

Adani Group, which is based in Ahmedabad, India, has denied the allegations, calling them “baseless.”

In May, the Securities and Exchange Commission said Adani, along with a nephew, had agreed to pay $6 million to settle a parallel civil fraud case.

“Without admitting or denying the allegations in the complaint, Gautam Adani and Sagar Adani each consented to the entry of final judgments, subject to court approval,” the commission said in its release.

The Treasury Department also announced last month that it had reached a $275 million settlement with a company founded by Adani, Adani Enterprises Ltd., for “egregious” violations of U.S. sanctions against Iran.