Agustín Rodríguez, explorer and leader of the Rodríguez-Sánchez expedition, was engaged in missionary work along the Río Conchos in northern Mexico. In the late 1570s he read accounts of the adventures of Álvar Núñez Cabeza de Vaca and heard from an Indian captive reports of populous settlements with a high degree of culture living to the north of Nueva Vizcaya. Intrigued by these stories, Rodríguez secured permission in November 1580 from the viceroy to mount an expedition to the region. The group, which included nine soldiers commanded by Francisco Sánchez, left Santa Bárbara in early June 1581; two other Franciscans, Fray Francisco López and Fray Juan de Santa María, accompanied the expedition. The Spaniards explored the southern portion of what is now New Mexico, going as far north as Taos and eastward to the Pecos River. Santa María was killed by an Indian war party, but the other two friars insisted on staying in New Mexico when Sánchez returned to Santa Bárbara in the spring of 1582. An expedition led by Antonio de Espejo that returned the following winter discovered that Fray Augustín and the other Franciscan had been martyred at Puaray by hostile Indians.