I dont think they are "affixed" to any theory yet, but I do think someone close is talking, and may be giving the story they "were given" by Casey to get their help to move Caylee.. I think it is more they are working through the most logical possibilities as they relate to the evidence and then exclude from there.
Btw, why do we suppose the clothing came from Tony's? She had been living at Amy's prior to 7/15, and no explanation as to why she moved out ot Tony's really, which his roomate had stated she used as a "remote event planning office.." Point is if the clothes were in her car in duffle bags, is there a duffle bag missing anyone is aware of? And why she driving around with dirty, smokey clothes for a few weeks?