COPENHAGEN, Denmark — The main suspect in a huge fraud involving public money was arrested on her return to Copenhagen after she voluntarily left South Africa, a Danish prosecution authority said.

The Serious Economic and International Crime unit wrote on Twitter that Britta Nielsen had landed in Denmark Friday, a day after a South African court freed her after she was arrested on an international extradition request.

Nielsen was arrested Nov. 5 in Johannesburg and had 648,700 rand ($46,000) in cash in her possession which was confiscated. Denmark sought her extradition, but the process was abandoned after she said she would voluntarily return to Denmark and face any charges.

Four days earlier, a man suspected in the same case also was arrested in South Africa as he was about to leave the country with two diamonds in his luggage.

The Serious Economic and International Crime unit said he, too, had returned to Denmark and was arrested. South African authorities have identified him as Nielsen's adult son, Jimmy Hayat. A Danish court has barred media in Denmark from naming him.

Nielsen, a 64-year-old civil servant, is wanted in a fraud case that caused a Danish government welfare agency to lose at least 111 million kroner ($17 million).

It was not clear how the money was stolen, but it appears Nielsen had privileged access to the agency's computer system. A preliminary probe says that at least 274 money transfers were made during 2002-2018.

On Oct. 10. Denmark's minister for children and social affairs, Mai Mercado, said Nielsen, who she said was "a trusted employee," had abused her position to commit systematic fraud during the period.