The one-time administrator of Dorchester’s Holy Family parish died suddenly after suffering a heart attack at his church in Canton. Fr. Mike McLellan, who was 64, had a long-standing connection to Dorchester from his early days as a priest. He served as the assistant pastor at St. Margaret’s Church and was assigned to St. Paul’s— now known as Holy Family. Most recently he was the pastor of Saint John the Evangelist Church in Canton and served as the chaplain for the MBTA Police. Fr. McLellan will be waked at St. John the Evangelist Church on Thursday from 2-8 p.m. with a bi-lingual Mass at 8 PM. A Mass of Christian Burial will be celebrated Friday, May 1 at 11 a.m. Interment will be at St. Mary’s Cemetery Canton.