IMO, most of the time when someone is taken, the abductor begins to think they need to get rid of the person because they are afraid they are about to get caught but they can't just let their prisoner go because they likely can identify them. OTOH, there have been quite a lot of cases where someone has been held for long periods of time (weeks, months, or years) and eventually escape or are let go. Unfortunately, we know whoever took Jayme has no compunction about killing. There is still a slim chance she's alive. I think she was the target, and I believe she was taken for sexual purposes. She may be able to build a relationship and be "useful" to him and liked well enough that he will keep her alive. She may eventually be able to escape.