COPENHAGEN, Denmark (AP) — A Danish prosecution authority says the main suspect in a huge fraud involving public money was arrested on her return to Copenhagen after she voluntarily left South Africa.

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.

The 64-year-old Danish 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.