Who do the people who actually know Alex Murdaugh think helped him facilitate the murder and/or clean up the crime scene/dispose of the evidence?

I feel like this isn't talked about nearly enough. At the end of the Netflix special, "Murdaugh Murders: A Southern Scandal", people including Blanca Simpson, Anthony Cook, Becky Hill, Morgan Doughty, and multiple others were asked if they thought Alex Murdaugh had help. All of them, to some extent, thought he had help. A clip that lives rent free in my head is the one featuring Blanca Simpson. Upon being asked the question she proceeds to say she doesn't feel comfortable answering that. It's as though she knows naming specific names will have consequences. Blanca Simpson was privy to so much information being in that house. I'm so curious as to who she specifically thinks played a role in all of this because I'd bet a lot that she's most likely correct. Who do you guys think all of these people have in mind? Who is Blanca most likely suspicious of? Clearly, they think Alex knows someone who would've helped him facilitate this which is terrifying. The only person that I keep fixating on is his brother John Marvin. In my opinion, based on his testimony, he's just as sociopathic as Alex. I found his testimony to be extremely theatrical, exaggerated, and manipulative. Is there any information as to where John Marvin was during the time of the murders?