He was involved as an expert consultant on seminary formation for the United States Conference of Bishops and other authorities for the next twenty years.
He continued to take an interest in the council which he had studied for his dissertation and wrote several articles on it for scholarly journals with Hispanic focus.
[3] Poole also researched the life of Pedro Moya de Contreras, the third Archbishop of Mexico, who had convoked and presided at the Third Mexican Council.
In 2004 the University of Oklahoma Press published the biography, Juan de Ovando: Governing the Spanish Empire in the Reign of Philip II.
In 1971 Poole was assigned to teach Church history at St. John's Seminary College, which at that time was administered by his religious congregation for the Archdiocese of Los Angeles.
Poole's writings regarding Our Lady of Guadalupe include the books Our Lady of Guadalupe: The Origins and Sources of a Mexican National Symbol, 1531-1797, an English translation of Luis Laso de la Vega's Nahuatl account of the apparition, Huei tlamahuiçoltica and a translation and critical edition of two Nahuatl plays about the Virgin.
In 2006 he published The Guadalupan Controversies in Mexico, where, along with other experts in the field, he disputed the historicity of Juan Diego, the Aztec man to whom the Virgin is believed to have appeared.