Martin of Arlington, formerly of Cambridge, January 14, 2011, Sean P. Martin, age 45. Loving father of Julia Martin of Brooksville, Maine. Beloved son of Marianne Martin of Billerica. Devoted brother of Paul Costa of Billerica. Grand nephew of Mary O'Connor of Cambridge. Nephew of Joan Castrucci, Paul Martin, and John Martin. Funeral from the John C. Burns & Sons Funeral Home, 305 Broadway, Cambridge, Friday, January 21, at 9:00 a.m. followed by a funeral mass in St. Mary's Church, Cambridge, at 10:00 a.m. Relatives & friends invited. Visiting hours, Thursday, January 20 from 4:00-8:00 p.m. Served in the U.S. Navy. Interment Cambridge Cemetery at a later date.