The flight attendant theory that gets floated around makes little sense to me because airlines book rooms in discounted corporate blocks. (Among other things that are totally absent from this scenario.)
I think given the emotional intensity flying has for many people, the odds a recent passenger would have remembered her would also have been high even if she was not working at the time of her stay at the Oslo Plaza.
Someone involved in something shady, who knew there would be a rush at that hour, and either took her chances or maybe bribed the young clerk to let her check in is my theory. Remember, she also extended her stay once she was already a guest at the hotel, in addition to changing her arrival dates prior. So more than ONE opportunity IN PERSON to ask "Jennifer" for ID and a credit card was missed. That smells like a bribe to me. I don't know about the rest of you, but she "got away" with it TWICE in person.....
The hotel is very close to the train station. And a very large mall is also right across the street, which was open when "Jennifer" was alive.
Oslo City : Offisielt nettsted til kjøpesenteret i Oslo
Possible she could have spent time here before or during her stay. My thought is this: "Jennifer" certainly timed her check in to coincide with a time when she would easily get away with not showing ID. I don't think that was just luck. I think it was planned. She was probably calling from within Oslo when moving the dates of her stay around. JMO!
Another question I have: If you speak English fluently, why are you using German for one of the calls to a hotel in Norway? I can understand if a guest was not comfortable with English, and possibly requested to use German, but then wouldn't they use German going forward? If "Jennifer" spoke both English and German fluently, it seems strange to use both with the hotel staff in Norway, a country with very high levels of English proficiency. This makes me again question if there were two women communicating with the hotel.
An affair makes sense, and could explain suicide, but it does not explain all of the missing pants/skirts/personal hygeine, etc Otherwise, I think a lot about the situation could point to "Jennifer" having an affair. It makes so much more sense than her being a spy. Perhaps the affair partner was the guy who stayed in the room across the hall who messed up when he spoke with the Norwegian press and mentioned "Jennifer" being dead the day before she was discovered deceased and the hotel having allegedly asked him about it? It is possible they had a fight, she killed herself (or he killed her), he panicked and left with the wrong bag?