A woman has been arrested woman over the fatal shooting of a US border patrol agent earlier this week, the FBI said. Teresa Youngblut, 21, from Washington state, was charged in Monday’s killing of border patrol agent David Maland in northern Vermont.

The suspects, a woman from Washington State and a German national, had both been under surveillance in the days leading up to the deadly encounter.

The shooting on Monday in Vermont near the Canadian border followed the surveillance of an armed couple who dressed in black tactical-style clothing.