Afraid of leaving DNA on the body to be found, an accidental killing by someone close to her who staged the scene/disappearance, or possibly revenge for something. Other than that, maybe a weirdo who collects bodies for some weird reason? It’s a lot to go through, taking an 84-year-old woman with mobility issues. It would help in getting you caught, drawing attention to yourself. It’s kind of hard to transport a body and not raise suspicion. There probably was some luck involved in this case too.But still… WHAT was the motive![]()