Although the hit-man theory has never really been taken seriously, or investigated in any detail, I still find it more feasible than imagining Sheila shooting the boys, then June, having to re-load, then chasing Ralph to the kitchen and beating and shooting him. Ralph was a tall, strong man - he wouldn't have just waited for Sheila to attack him. There is no evidence that he tried to leave the house or protect himself in any way - and if shots had already been fired, Ralph would have warned JB to stay outside. In all reality, asking JB to "come quick, your sister's gone crazy..........." would be inviting him to be also injured or killed. IMO.