When I say OK I mean in the legal sense not morally!
During JB's interviews under caution DS Jones said to JB:
"I will tell you now that it has been proved that your sister Sheila did not kill herself and in fact was murdered along with your parents and the twins, is there anything you wish to say about this?"
From the CoA doc:
46. From the pathological evidence alone, the pathologist could not say, one way or the other, whether Mrs Caffell had been murdered or had taken her own life.