Arthur Allan Thomas' brother carried out his own forensic tests to discredit the evidence that convicted his brother.
This week, Ray Thomas has revealed he planted shell cases in the Crewe garden - replicating the actions of detectives investigating the case. He proved buried shell cases would discolour compared with the shiny case presented to the court.
Arthur Allan Thomas was twice convicted over the deaths of Harvey and Jeannette Crewe in 1970, and then pardoned. A Royal Commission of Inquiry found a shell case from Thomas' gun had been planted in the Crewe garden by police officers.
The killings left baby Rochelle, 18 months, abandoned in her cot. Now in her 40s, she has asked police to review the case.