I’m hopelessly behind, but have watched the presser and read the last few pages in this thread. My new theory is that she connected with someone from college or her online summer class. She left with him or her voluntarily, but then things took a dark turn. She may be held against her will, or she may already be deceased. LE has traced the individual thru Mollie’s electronic communications, but don’t know current status or location. They are hoping to flush the person out, either thru tips, or fear. If the person thinks LE knows she connected with him/her, maybe they’ll come forward. By saying they don’t know whether she left voluntarily, the person may think there’s an out — e.g., “I did pick her up, but I dropped her off at her mom’s house; don’t know what happened after that.”
TOTAL speculation on my part.