Archbishop Pierre has served in the Diplomatic Corps of the Holy See for most of his professional life. The native of Rennes, France, studied in Madagascar, France and Morocco before attending seminary. Beginning in 1977, his service in the Diplomatic Corps brought him to posts representing the Holy See in New Zealand and the Islands of the Pacific Ocean, Mozambique, Zimbabwe, Cuba, Brazil and at the Permanent Mission of the Holy See to the United Nations in Geneva, Switzerland.
Since 1995 he has served as apostolic nuncio to Haiti and as the papal representative to Uganda and Mexico. He was named to his current post representing the Vatican to the United States in 2016.