Mugford is a witness. There were other witnesses as well. Including Jeremy who was unconvincing.
The mountain of 'circimstantial evidence is that Jeremy phoned the police. If Neville had not phoned Jeremy, Jeremy is guilty as 'Sheila' had gone crazy. It was him or Sheila. There is no evidence Neville phoned Jeremy.
He had a bike at home, knew the routes & had loaded a gun that evening. He phoned Mugford & knew how to get in WHF through windows. He knew how to exit & lock from outside.
Unconvincing because he had nothing to tell. How on earth can anyone,whose faced with a barage of questions,be expected to answer,when they know nothing of what happened that night ?
The bike stayed put,,and for all we know,Neville may have been in the process of securing the rifle knowing that the twins were staying there.
He phoned JM because she was his only contact,as after all,,his relatives weren't exactly supportive at any time,even before the tragedy,they hated him like poison.
If Jeremy had committed the murders,,why did he bother ringing the police anyway ? Why not just turn over and forget about it ? A psychopath would have done,,and it's been well established that Jeremy isn't sick in the head/mind.He hasn't even shown signs of violence in prison.