Those who know Jessica say she never does anything without her grandmother's permission.
Her first thought would be of her grandparents there in the house with her, to run and awaken them, too. Whoever it was would need a story to cover that, like, they already know and are outside, or they already went to the hospital and left me here to take you.
Something to cover it, and then, it had to be somebody she knew for her to open the door or go with them, period, and someone who convinced her about the grandparents' whereabouts.
Yes, the police must be following up big time and even shadowing some people. As you, sadly, I fear her fate is cast. Hope we are wrong.