IMO the vehicles will bring the answer. Apart from Christina's vehicle, am seriously considering if perhaps someone-of-interest may have been driving their father's car that night. (Phaeton was the son of Helios, or so the Greeks tell us) That would've thrown a spanner in the works if LE were looking for a particular vehicle belonging to a certain person whom was on their radar. LE need to check whom was driving which vehicle that night. Hope that they have checked.
IMO, if Christina was rekindling an old flame (for personal agenda reasons), then she certainly would not have wanted to be escorted to where her car was located if she didn't want anyone to know what she was up to. She may have a history of parking in that particular part of the garage; known by those close to her - particularly if this part of town had been her 'old stomping ground'.
The fact that several of her initial social-group had parked in close proximity on their way to their meeting place might suggest that this is correct. That's thinking - safety in numbers - something we all do. What isn't safe is when the return to their vehicles is not handled in a similar manner - as it did not on this occasion.