Their daughter’s boyfriend Jonathan Jones was found guilty of their murders and sentenced to life in prison in 1995, but was later freed on appeal.
Mr Jones, who was a self-employed recruitment consultant, had told police he had taken the day off work on the day the Toozes were killed.
He said he had gone to Orpington, Greater London, to look for office space to rent, but police could not find anybody who had seen him that day.
His partial thumbprint was also on a cup and saucer that had been found in the couple’s living room.
He was arrested that December, five months after the murders.
Cheryl Tooze stood by him, moving in with his family in Caerphilly after his arrest.