Homicide squad detectives arrested a 58-year-old Rowville man on Thursday relating to the murder of 71-year-old Doris McCartney and her brother Ronald Swann, 69. The man was escorted into police custody on Thursday morning and will be interviewed by detectives this afternoon. He was photographed in a police vehicle wearing a baseball cap covering his face. Last week the Herald Sun revealed police were announcing a $1 million reward over the Moorabbin murder. Ms McCartney and Mr Swann were found strangled in their shared Keith St, Moorabbin house on October 22, 1989. There were no signs of forced entry and nothing had been taken.