[1] He fulfilled assignments in Italy, Great Britain, the United States and Austria, and also served as a delegate at the International Atomic Energy Agency in Vienna.

[4] Prigione played an important role in giving the Mexican episcopate a more conservative profile in line with Pope John Paul II's repression of liberation theology and reassertion of papal primacy.

When Archbishop of Chihuahua Adalberto Almeida y Merino denounced electoral fraud in the 1986 gubernatorial elections, he announced the closing of churches in the diocese on July 20.

The Holy See and Mexico established diplomatic relations in September 1992 after lengthy negotiations and major changes to the stringent anti-clerical provisions of the Mexican Constitution of 1917 in December 1991.

[6][7] During his visit to Mexico in May 1990 Pope John Paul had announced an upgrade of Prigione's status from apostolic delegate to permanent special envoy.

In December 1993 and January 1994, Prigione secretly met with two drug traffickers the government had identified as culpable in the assassination of Cardinal Juan Jesus Posadas Ocampo in May 1993.

It said Prigione had united the Church with the government "to disrupt everything that smells of liberation theology and all pastoral work that brings the faithful closer to political participation or social organization".