Indian police said on Saturday they had arrested the suspected mastermind behind a call centre scam run out of a Mumbai suburb that targeted thousands of Americans and netted more than $300 million.

Sagar Thakkar, 24, also known as Shaggy, was arrested at Mumbai’s international airport in the early hours of Saturday after he flew in from Dubai, Mukund Hatote, a police officer on the case, said.

In October, the U.S. Justice Department charged more than 60 people in India and the United States with participating in the huge scam where call center agents impersonated Internal Revenue Service, immigration or other federal officials and demanded payments for non-existent debts.

The department said at least 15,000 people had been targeted by the telefraud that was run out of India.

The scam – which ran for more than a year – was blown open in early October, when Indian police raided a host of call centers in the Mumbai suburb of Thane and detained over 700 people suspected of involvement in defrauding Americans. Other call centers involved in the scam that operated from the western city of Ahmedabad were also raided and shut down by authorities.

At a news conference on Saturday evening, Thane Police Commissioner Param Bir Singh said Thakkar, who was charged in December along with others, had fled to Dubai in October following the raids and that he had also spent some time in Thailand over the last six months.

Thakkar, wearing blue jeans and a checked shirt, was presented to media on the sidelines of the press conference, but his face was covered with a black cloth.

Singh said he had interrogated Thakkar and was “impressed with his knowledge of the U.S. and Indian system.” Singh said Thakkar had confessed to his involvement in the scam.

Singh said Thane police have so far charged 400 people in the case, and about a dozen of them are in custody.

Thakkar was listed as a call centre operator and payment processor in the U.S. Department of Justice indictment that charged the defendants with conspiracy to commit identity theft, false personation of an officer of the United States, wire fraud and money laundering.

According to the indictment, call centre operators threatened potential victims with arrest, imprisonment, fines or deportation if they did not pay taxes or penalties.

Payments by victims were laundered by a U.S. network of co-conspirators using prepaid debit cards or wire transfers, often using stolen or fake identities, the indictment said.

U.S. and Indian authorities have been working together on the investigation. The United States had said it would be seeking the extradition of the alleged scamsters based in India.

Indian police have previously said that Thakkar led a lavish lifestyle, frequenting five-star hotels and driving around in expensive cars.