I liked the comment in the CNN series from his friend - he said (paraphrasing) "I don't think anyone else did it besides Alex because nobody else in Hampton is crazy enough to kill a Murdaugh."Can someone even imagine a scenario in which a person or persons other than AM committed the murders. What kind of criminal comes to the property to kill a mother and son and doesn't bring his own weapons and, instead, assumes he will find suitable weapons at the property? I do think there is a reasonable possibility that a second person assisted AM with the crime. In other words I don't believe beyond a reasonable doubt that AM acted alone. But that does not absolve him of guilt for the killings.
In other words - given the power that the Murdaughs have, it is impossible to find someone else that would have the balls to kill a Murdaugh.