A man has been arrested over the murders of a brother and sister in Melbourne more than 30 years ago.
Doris McCartney, 71, and her brother Ronald Swann, 69, were found dead at their Moorabbin home in October 1989.
A 58-year-old Rowville man was arrested on Thursday, following the offer last week of a $1 million reward to help solve the case.
The man is being interviewed by detectives and no charges have been laid.
