If they did kill him, which I think's unlikely, where's the body? He was a big lad. They were both ex-cops so would have some knowledge of police procedure. They weren't daft enough to hide it in the garden or the house. Maybe miles away but that would mean them carrying him. Unless sister helped. Dad's a biggish guy but not Doris. Are there any lakes near there and have the police ever sent divers in? I still think he was led away from the toilets whilst his mum was still inside. Then who knows.