I agree that the family could have heard a reference to accelerant and taken it as fact. But I still don't get AA's reference to it.
FWIW, I feel like the accelerant theorizing had to come from somewhere ... IMO, it's not something that one would just pull out of thin air. Maybe I'm wrong here, but I don't feel it's something that a parent would gravitate toward. The burning itself seems horrific enough ... would a parent (or even a friend/acquaintance) think of that without an outside suggestion? If so, I feel like there should be a reason, i.e., a person suspected that someone wanted to "silence" or make an example of her. (I don't lean toward this being gang-related, BTW ... just saying that the accelerant statement confuses me. A doctor suggesting it makes it more logical, IMO.)
it must have been said at the crime scene in one way or another, whether it was true or confirmed or not, although I can't believe LE told AA about it. I bet the tow truck driver told AA as he would have overheard it while on scene. I can't believe LE would be so unprofessional.