Gardai were last night treating as suspicious the death of an elderly man at his home in Raheny, north Dublin. He had suffered head injuries.He was found by his son, who called to his apartment at Bettyglen, off Watermill Road shortly after 5 p.m.The State Pathologist, Dr John Harbison, is to carry out a post mortem this morning. Gardai last night said there were no obvious signs of a break-in but were preserving the scene for inspection today.