補佐司教
Popp was born in Nada, Texas in 1917. He was ordained a priest on February 24, 1943 in San Antonio, Texas. Popp was appointed Auxiliary bishop of the Archdiocese of San Antonio Texas along with Titular Bishop of Capsus on June 3, 1983 and consecrated July 25, 1983. Popp retired as Auxiliary bishop of San Antonio March 23, 1993. He died on June 27, 2014, aged 96.