Surely with a case like WHF where five people are found dead and one of them is holding the murder weapon, you have to conclude murder/suicide unless it was possible for someone to break in and kill everyone before staging the scene! That was the only other possibility, and to rule that possibility out someone had to determine if the house had been securely locked from the inside!
That was the only action needed to confirm murder/suicide, the one and only action.
And that was exactly what Taff did!! He took the only action 'needed' in order to rule out foul play from a third party, as it were.
And Taff certainly checked to see if all doors and windows were firmly secured, hence any chance of an 'intruder' carrying out the shooting and then exiting the house should have been ruled out, yes?
Now when we hear of all these police officers who thought that Sheila wasn't the killer from the start, just what part about the house being securely locked from the inside didn't they understand?
No, in reality, Taff did the only thing that was neccessary to rule out a third party killer before leaving, hence Sheila had to be the killer
And once Taff did check the house was secured there was nothing else for him to do, he wasn't a scene of crime officer was he, so why wait around?
BUT!! alas the jury were told that just how JB entered or exited the house was of little importance!!
What if the shooting had taken place in a locked bank vault with a timer?