Overview
- South Wales Police said the man was arrested on Wednesday and remains in custody as detectives question him.
- Investigators have not released further details about the suspect and no charges have been announced.
- Harry, 64, and Megan, 67, were found shot and concealed in a cowshed at their Llanharry farmhouse on 26 July 1993.
- Jonathan Jones, convicted in 1995 over the killings, had his conviction quashed as unsafe by the Court of Appeal in 1996.
- Senior Investigating Officer Det Supt Mark Lewis said inquiries continue and urged anyone with information to contact police.