Police found their bodies hidden under bales of hay in a cowshed at their isolated smallholding Ty-ar-y-Waun (House in the Meadow) after their daughter, Cheryl, had raised the alarm when there was no answer to the nightly phone call she made to her parents.
Jonathan Jones arrived by car in the early hours to help the police search and was allowed inside the house.
During Mr Jones's trial, defence lawyers argued that it was possible this was how half a fingerprint of his came to be found on a teacup in the kitchen.
Mr Jones maintained that on the day of the murders he was in Orpington, Kent, looking for office premises to rent for a new business venture with Ms Tooze, whom he first met in 1983 while studying at the Polytechnic of Wales in Treforest.
His barrister decimated the prosecution case this week when he told the Court of Appeal about a shotgun surrendered to police which "could have been used" in the killings. The gun was handed in to Tonypandy police station on 22 September 1995 - five months after Mr Jones had been jailed for life for the murders.
Police traced the single- barrelled pump action weapon back to a farm worker, Jeff Ayres, who was known to the murder victims.
John Rees QC told the three appeal judges that police investigating the murders had questioned Mr Ayres, who lived near the Toozes, shortly after the killings and he had denied owning a shotgun.
"This was a lie. At the time of the killings it was hidden in his attic and could have been used in the murders," Mr Rees said, adding that Mr Ayres had been working for the Toozes shortly before the murders.
Mr Rees said the gun, which had been offered for sale with ammunition for pounds 30, was handed in to police by a workmate of Mr Ayres who told them he wanted nothing to do with it because it was used in the killings.Reuse content