 The forces of Dr. José Gaspar Rodríguez de Francia, the strong man of Paraguay, abducted Bonpland after killing Bonpland's estate workers.Bonpland was accused of "agricultural espionage" and of threatening Paraguay's virtual monopoly on the cultivation of yerba mate.Despite international pressure, including the British government and Simón Bolívar's, along with European scientists including Humboldt, Francia kept Bonpland prisoner until 1831.