In 1968, Museum ethnologist Dr. Bernard Fontana asked Helga if she would like to document the cleaning of the three major altars of Mission San Xavier del Bac, an 18th-century Franciscan mission church located southwest of Tucson, within the San Xavier District of the Tohono O'odham reservation.

Teiwes worked with the mission's caretakers to document the painstaking cleaning processes. This experience inspired her to return many times to photograph this "White Dove of the Desert." As well as recording the interior and exterior features of the magnificent Spanish-Baroque style building, she visually interpreted it as a living center of religious life for the O'odham people.