Bamber's footprints and fingerprints will be all over the house. He was a regular visitor. Either sneaking through windows to look at wills, or popping over for supper and a rabbit massacre. So no possible joy for the police here.
Bamber had a month to dispose of clothes. Even so John Hayward found human blood on Bamber's jacket, bathrobe and in his car.
The crime was committed by Sheila or Bamber. There is a mountain of forensic evidence showing it was not Sheila. Which automatically shows it was Bamber.
June being shot with her head on the pillow is forensic evidence pointing to Bamber rather than Sheila.
There is the silencer evidence which shows beyond doubt it was Bamber.
There is the found hack saw which Bamber admitted using to get in and out of WHF. But apparently not on the massacre night.
There is the discovery that the kitchen window could be banged shut from outside.
No one can explain how Sheila could have committed the massacre to match the crime scene. Which shows Jeremy's certain guilt.