Father Juan Bautista was from Cizúrquil, Spain. Although the accepted spelling of today is Beldarrain, he spelled his name Velderrain, . In the port city of San Sebastián he took his first vows in 1763. Less than six years after, at the convent grande in Vitoria, he volunteered for the Mission of 1769 to the College of Querétaro. He was a tall Basque with black hair and grayish eyes.
By 1773 he was missionary to the problem Pimas Bajos of Tecoripa and Suaqui. He had faced down drunken Indians, and more than once talked them out of deserting but, more than that, he had built a church. Before his time the Pimas Bajos known as Sibubapas had revolted and joined the Seris in the Cerro Prieto. When these rebels surrendered, the Spanish consented to build them a church at royal expense to replace the ruin at Suaqui. This Beldarrain had accomplished in the face of a thousand adversities.
In 1776, the College of Querétaro negotiated the transfer of the eight despised Pimería Baja missions. The Franciscan province of Jalisco took them. At each one the Querétaran in charge signed over to his blue-robe replacement a census of the populace and an inventory of the mission’s material resources.  Father Juan’s mission was one of these.
Father Beldarrain took refuge at Tumacácori. He joined Pedro Arriquibar for a couple of months. A 70 percent drop in baptisms at Tumacácori from 20 in 1775 to 6 in 1776 told the tale.
The soldiers had left Tubac. Captain Hugo O’Conor had written the order in December 1775.
By early 1777 the lanky friar would move north to San Xavier del Bac and apply himself to learning Piman under Father Garcés. Not long after Garcés left, Beldarrain would begin construction of the White Dove of the Desert at Bac.
Well before the completion of the church, Father Juan Bautista would die suddenly, May 2, 1790, vomiting blood. Father Carillo of Tumacácori would reach him too late to administer the sacraments. Beldarrain’s replacement at Bac, Father Llorens, carried forward the construction.
 Ibid. Arricivita, Lista, 1769. Madoz, Diccionario, Vol. 6, p. 437.
 Building contract for the church at Suaqui, real de San Marcial, April 11, 1774, AGN, PI, 247. Velderrain to Pedro Corbalán Suaqui, May 25, 1774, and Corbalán to Velderrain, Alamos, May 30, 1774, ibid. Velderrain to Juan Joseph Lumbreras, Tecoripa, July 2, 1775, ibid., 96.
 The missions turned over were: Tecoripa (August 16), Onavas (September 3), Cumuripa (September 9), San José de Pimas (September 10), Ures (September 26), Opodepe (October 6), Cucurpe (October 10) and Pitic de Seris (n.d.). Fernando Mesía and Francisco de Salas Carillo, Mexico, July 3, 1780, AGN, PI, 258. (Bucareli) to Crespo, Mexico, May 25, 1775, and Crespo, Índice de los asuntos, Horcasitas, October 24, 1776, ibid., 96. Arricivita, Crónica seráfica, pp. 460-61.
 Garcés to Ximénez, Tucson, February 19, 1778, CC, 201.20. Father Francisco Iturralde, Visita de las misiones de la Pimería, September 5 to October 30, 1797, ACQ, CSCQ. Libro de difuntos, 1776-ca. 1850, ACQ. Beldarrain entered only a single baptism in the Tumacácori book, on December 5, 1776. DCB. Early in 1777 he and Father Joaquín Belarde were looking after San Xavier for Garcés. Garcés to Ximénez, Tubutama, February 3, 1777, CC, 201.19.