I think this just means that they are certain it is HG (i.e. the parents know those are her pants). I don't think they are dragging their feet, but I also think they are carefully strategizing every single thing they do right now.
Get out of here. Seriously?? Longo has said over and over and over and over that he made a promise to Hannah's parents, and they deserve this closure, etc. I don't think he meant "whenever the ME feels like it."