If this crime had happened in this day and age, the silencer would not have been allowed into evidence at trial.
First, five different police officers had searched the gun cupboard without finding it.
Secondly, it was found by people who stood to gain considerably by Jeremy being found guilty.
Thirdly, the people in the house when the silencer was found all have differing accounts of the events. Fourthly, they brought the silencer home with them, handled it, discussed what to do with it.
There was a POSSIBILITY of tampering - it would never enter into evidence today. Not saying anyone did anything other than what they have talked about, like for instance scraping a flake of blood off of it with a razor blade, because it was "fascinating" (!!), but the mere possibility of tampering would render that silencer unsafe evidence.