Born James Aloysius Hegarty on October 12, 1902 in the Kensington neighborhood of Philadelphia, Pennsylvania. He was the son of William and Catherine Sullivan Hegarty. He attended Ascension Elementary School (1909-1916) and Roman Catholic High School of Philadelphia (1916-1917). In 1918 he decided to enter the Passionist Preparatory Seminary at St. Joseph’s Monastery, Baltimore, Maryland. He completed high school and college preparation at Holy Cross Seminary, Dunkirk, New York in 1921. When he professed his vows on August 15, 1922 at St. Paul’s Monastery, Pittsburgh he received the name Malachy. He was ordained a priest on May 25, 1929 by Archbishop Thomas J. Walsh at the Newark Pro-Cathedral. Father Hagerty then went on to pursue post graduate studies in Electric Engineering, Mathematics and Physics at Canisius College, Buffalo, New York and The Catholic University of America in Washington, D.C.
From 1929 to 1941 Father Hegarty was Professor of Mathematics and College Physics at Holy Cross Seminary, Dunkirk. From 1939 to 1941 he was also Vicar at Holy Cross Seminary. During these years at Dunkirk he was also chaplain at St. Joseph’s Home for Children. In 1941 he was assigned to St. Ann’s Monastery, Scranton, Pennsylvania. In 1942 he became a military chaplain. where he served with the 87th Infantry Division during the African and Italian campaigns. He was decorated for his service with Three Battle Stars, the Victory Medal, and on July 11, 1945 was awarded the Bronze Star and left the military with the rank of Lieutenant Colonel. From 1946 to 1953 Father Hegarty was pastor of St. Michael’s Monastery Parish. He then was assigned to Immaculate Conception Monastery Church, Jamaica, New York. At that time he also served as assistant chaplain at the Creedmoor Health Facility in Queens, New York. From there he was assigned to St. Mary’s Monastery, Dunkirk and when Dunkirk closed he returned once again to the Jamaica, New York monastery. From 1967 to 1976 Father Hagerty suffered from poor health. In 1973 he was transferred to the Passionist infirmary at St. Gabriel’s, Brighton, Massachusetts. He died on September 20, 1976.