The police giving who the blood? Relatives?
Well,it may be as simple as this Cutes.Once the cops decided that JB was going down,they decided they would beef up the evidence against him.They had nothing at all linking him to the crime scene,so they went over the general scenario of what happened and some bright spark came up with the silencer plan.
They had Sheilas blood,they had the silencer and they had witnesses more than willing to say they found it in a rather obscure place that the police had simply overlooked.Someone also remembered that some sort of struggle took place in the kitchen and the scratch marks idea sprang to mind.Perfect,that would nail Bamber good and proper.
It didn't directly place Bamber at the scene,but it proved someone put the silencer back after Sheila was dead,so,same thing.If Sheila wasn't the killer JB was.
So,for all we know ,the police may have simply given the relatives a script,the silencer may never have been in their possetion at all.It would certainly explain all the different statements of who was present when it was found and the different descriptions,ie the blob of jam,the hair,paint,no paint.Who phoned the cops,who handed it in etc,etc.
Then when Julie came forward,prompted by her friends,for whatever reason,this was perfect for the police.They told Julie that they had proof of JBs guilt,so she was more than happy to help them by doing her duty to help convict an evil monster,especially after certain guarentees to herself and Susan.
We know a different cop was appointed to carry out the JB murder investigation,but why?Everyone had been interviwed for the murder suicide,all the evidence had been gathered,yet all that was shelved.Was it because Ainsley was willing to bend the rules,and also obtain new witness statements painting a very black picture against Bamber.
So what we have actually ended up with really,is similar to starting watching a film half way through and trying to work out what happened at the beginning.Until the original investigation file is disclosed to shed some further light,there will forever be doubt of Jeremy Bambers guilt.