O’BRIEN , WALTER S. age 75 died on May 22nd in Ft. Myers Beach, Florida. Formerly of South Boston, he is th e beloved father of Maribeth O’Brien of Darien, Connecticut. the loving grandfather of Madeleine, Aaron and Audrey Sears, and the former husband of Rosemarie Rizzo O’Brien. He was the son of Mary S. and John F. O’Brien, brother of the late John and William O’Brien and Elizabeth Bulens. He is survived by his sisters Mary Slaney of Florida, Alice P. Grady of Sandwich, Madeline Simpson of Quincy and many loving nieces and nephews. Walter was an avid sailor and, along with both John and Billie, he was a proud member of Ironworkers Local 7 in Boston.