Personally, I think that too far-fetched to be remotely realistic. There is no evidence at all, anywhere, in any form what-so-ever, that suggests state intelligence, from what I can see. The gun is exactly the type of weapon that is recovered from common criminals all the time. It's made from bits of other guns with identification numbers removed which is what criminals often do. Given the way in which the chambering identification was marked (9x19) I suspect that it was a military barrel (or whole gun at that point) purloined by a soldier who removed the numbers to prevent tracking it back to his unit and potentially to him.
There is, to my mind, everything to suggest that it wasn't an intelligence operation; if she were simply someone they wanted to keep quiet then why do it in this very public way - a hotel room which leaves a body and massively increases the chance of the assassin to be caught? We know that she spent almost a full day away from her room. If some intelligence agency wanted her dead then they had ample opportunity to do it much more discreetly than shooting her in a hotel room. Done correctly any operative would be out of the country long before her body was found, if it even ever was.
As I've mentioned previously, the most likely and least complicated answer is almost certainly the correct one. That answer is that she shot herself. The very fact that she was still gripping the trigger to its farthest point of travel reduces the likelihood of another person shooting her by a massive degree. The fact that there are other rather strange facts associated to this; the lack of documents; the sparse amount of clothing; virtually no personal items such as makeup or toiletries; the fact that she checked in seemingly without leaving any form of payment and suchlike are merely strange connections/facts/occurences and not much more. I think they suggest that she had contact with someone, or visited other venues where she had more possessions available to her but they are not suggestive of an intelligence operation, as far as I can see. The fact is that we simply do not know why those strange facts exist, they are "strange" because we don't know how they relate to her and they do not, in themselves, suggest any outside influence on her death, let alone at the hands of a sovereign state or other.
The most telling thing about this whole affair is the check-in, to be honest. I'm not saying that it's impossible but I would suggest that it is enormously unlikely that she was able to simply "hit lucky" and manage to check-in to a very modern, ultra-luxury hotel with absolutely no form of identification or method of payment without someone at the hotel allowing her to do so. I doubt that any country sends espionage agents out on a random possibility of them being able to check-in to places with no form of ID or payment and in possession of nothing other than skimpy clothing and a bag containing a large military handgun and some ammo. The only reasonable explanation for her checking-in like that was that she was allowed to do so by someone. There are only a few possibilities to explain that, I think; A) She was known to the hotel (or its reception staff) as a regular who had been allowed to do this in the past; B) She was checked-in like that because someone else known to the hotel (or its reception staff) asked them to do so and was picking up the room bill; C) She was a friend/relative/girlfriend of someone who worked at the hotel - although that is really a variation of the first part.
One thing that I don't recall ever being suggested is - was she actually Norwegian or had she been living there a long time? That would entirely negate any questions as to international travel with no documents and would perfectly explain why she had so few clothes. She may have been simply trying to get some time to herself and may have lived locally? Perhaps escaping an abusive relationship for a few days/forever? If anyone has seen the recent Netflix documentary on Tina Turner's life (and if not then you should, it's really good and she is an absolute legend!) then you'll know that that is exactly what she did when she escaped her psychotic ex-husband - she ran across the freeway to the nearest hotel told the manager who she was and that she had 19c in her purse but would have someone wire him the money the next day if he let her stay. Now, I'm not saying that that was the case here but it is at least a very reasonable proposition and far, far more likely than anything to do with spies.
