She should be arrested for conspiracy....
Probably not an option unless the package contained something unpleasant. If not then what are you going to charge them with? Possession of marzipan?
The point is you're not supposed to take anything on a flight from anyone you don't know.
While I understand that check-in staff have to ask the same questions about 'Who packed your bag' and 'Did anyone give you anything to take on board' a thousand times a day, it worries me that they don't seem to stress the importance of the question. Makes me wonder how many passengers genuinely stop to think before answering.