Jeanette and Harvey Crewe were shot dead in their home and their bodies bundled up, weighted down and thrown into the Waikato River.
Their bloodstained home was discovered by Mrs Crewe's father Len Demler who was to become a prime suspect in their deaths but police eventually arrested and charged Arthur Allan Thomas.
Mr Thomas, who pleaded his innocence from the outset, was nevertheless convicted and sentenced to life imprisonment. This was confirmed at a second trial but the evidence against Thomas was considered flimsy and circumstantial. After serving nine years in jail he was given a full pardon and awarded compensation.
Part of the credit for his release went to British author David Yallop who published a book on the case entitled Beyond Reasonable Doubt.
It helped convince then Prime Minister Rob Muldoon to have Mr Thomas pardoned.
Mr Thomas bought a farm elsewhere in the Waikato, remarried and has built a new life for himself and his family.