Melgarejo left Italy on November 1, 1540, on an expedition led by Álvar Núñez Cabeza de Vaca to Río de la Plata [REF].
In the late 1540s Melgarejo organized the election of his relative Diego de Abreu to the post of Governor of Asunción, deposing Fernando Mendoza, who had been appointed governor by de Vaca's deputy [REF].