Based on the facts of the case, research and tests the so-called silencer evidence was a two-pronged assault by different parties at different times all believing Bamber to be guilty. And it doesn't include the relatives.
1. The relatives, including AP, raised the silencer very early on in the investigation. Hence, on 8th Aug Bamber was asked to complete a further wit stat about this very subject. DS Jones, the only dissenter from the murder/suicide theory, who was utterly convinced Bamber was responsible, could see how incriminating the silencer could be. DS Jones had access to WHF on 9th Aug when he handed the keys over to the relatives and briefed them on the alarm. As an experienced officer he knew that small bloodstains were incapable of being typed so he had all the material necessary for contaminating the silencer: blood, hair, paint (scratches). When it arrived at the lab it was incriminating for Bamber but didn't link anyone directly until the flake, aka set of test results, appeared a month later.
2. DS Jones working away in the background knew he needed something else to bolster the case ergo the chief prosecution witness. Now DCI Ainsley is heading up the investigation. Believing the evidence against Bamber to be reliable he is aware it is probably not enough to secure a conviction. He goes to head of lab, Ronald Outteridge, and hey presto a set of test results are produced said to have come from a flake of blood found inside the silencer caused by the little known phenomenon back spatter. The test results are a match for Sheila's blood groups alone. Bamber's back is now firmly up against the wall. Hence he was charged and remanded in custody. Over to defence counsel...
