Born to Mr. Lorenzo and Agostina in 1906, Orestes Marengo, after completing his preliminary studies, joined the Salesians at Valdocco in 1919. He was selected to come to Assam. He and his companions arrived at Shillong on the 22nd December 1923 under the leadership of Fr. Stephen Ferrando sdb. Archbishop F. Perier ordained him a priest on the 2nd April 1932 in the Church of the Most Holy Redeemer, Shillong. As a priest he toured the whole region and did real wonders. On 23rd July 1951 he received the official communication of the erection of the Diocese of Dibrugarh and his nomination as the first bishop of Dibrugarh. His Episcopal ordination was held on 27th December 1951 at the Basilica of Mary Help of Christians in Valdocco, Turin. On the 18th May 1952 Bishop Marengo was solemnly installed as the first Bishop of Dibrugarh. He was transferred to Tezpur in July 1964 and left for Tezpur on the 27th August 1964, after presenting his successor, Bishop Hubert D' Rosario sdb, to the people. Bishop Marengo had for his Episcopal motto: TO SEEK SOULS.

Rt. Rev. Robert Kerketta was born on 22nd October 1932 at Kacharigaon, Rangapara in Sonitpur district of Assam. He made his first profession as a Salesian on 24th May 1951 at Yercaud. On 11th February 1963 he was ordained a priest at Turin, Italy. On 21st May 1970 he was elected as the 3rd shepherd of Dibrugarh and his Episcopal ordination was held at Dibrugarh on 18th October 1970. After 10 years of hard work in Dibrugarh he was transferred to Tezpur on 31st January 1981.His Episcopal motto is: TRUST IN THE LORD AND DO GOOD.

He was born on the 22nd October 1936 at Palai, Kerala. He was ordained a Salesian priest on 2nd May 1963. On 13th July 1981 he was elected Bishop of Dibrugarh and his Episcopal ordination was held at Dibrugarh on 29th November 1981. He was transferred to Guwahati as its first Bishop on 12th August 1992. AT YOUR WORD I WILL LET DOWN THE NETS is his Episcopal motto.