***the fact there was a second duvet found in her room that hadn't been there before is a bit odd, isn't it?***
As a norwegian I can clarify some of the details in case the coverage doesn't translate well. I'm also currently employed by a large hotel chain in Norway and my hotel is located in the outskirt of Oslo.
The rooms locking system detected the times a keycard was used to open the door to the room. I'll leave the times with possible explanations at the bottom of my comment.
Verdens Gang (VG) and Dagbladet (DB) are not typical tabloid newspapers, and they have a good reputation so the information in them is credible in my opinion.
She/whoever was in the room pressed ok on the remote to let the reception know that she had read the message.
The Winchester branded ammunition found in the bag was for the handgun that was used.
The handgun was a 9mm Browning semi-automatic produced in Belgium between 1990 and 1991.
She did not show any passport or other form of ID and asked to pay for her stay in cash, but the only time she actually paid for anything was when she gave an extra large tip for her food service (50 kroner, approx. 8 dollars at in 1995).
The door was locked from the inside and the keycards used to open it was left inside.
There was a second comforter that is seen in the pictures of the crime-scene, but it was never investigated.
The coroner claimed it was suspicious how there was large amounts of blood spatter, but none on the hands of the victim. She also had no bruising on her hands from the recoil of the weapon, nor any gunpowder residue.
Most of the evidence was thrown out between the first investigation and now, and the hotel threw out everything from the room as soon as the police finished gathering what they thought was necessary. This includes the second comforter as the police never filed it as evidence. As of now the police have dug up her grave to look for more evidence.
The keycard is not necessary to get out of a room, but you have to use it to get in. Here's a list of times a keycard was used to open the room.
At 22:44 on Wednesday, Jennifer opened the door to room 2805 for the first time. A little later, she (or someone else) must have left the room, because the card was used again at 00:21.
The next morning, Thursday, the card was used at 08:34. It is likely that she had eaten breakfast, but I have yet to find any witness accounts of it.
On Thursday around 13:00 the room was cleaned by Vigdis Valø and a 19-year old helper. They both agreed the room was empty in the interrogations that happened the next week. The door was not opened again until next morning at 08:50, neither by employees nor guests, which means Jennifer left the room once between 08:34 and 12:44 on Thursday, and didn't return until 08:50 the next day.
The next use of a key card was Friday at 08:50. This was a new key card code, so she must have been by the reception and extended her stay before this. A hotel employee saw her go into the room and just afterwards hang a "Do not disturb" sign on the door.
That card was last used at 11:03 the Friday morning.
Friday evening at 20:06, Jennifer ordered food from the hotel's room service. At 20:23 the food was delivered. Kristin Andersen, who brought the food, noticed that the room was very tidy. The room looked untouched, the bed as well. She used the word "sterile" in her testimony (?) on the case.
A security officer went to check on her. He heard a gunshot seconds after knocking on her door, and believing that two people were inside the room, he went back down and called the police instead of investigating himself. They found her body half an hour later.
The comment has been edited to correct errors and add more information.
https://www.reddit.com/r/UnresolvedM...d_dead_in_her/ 
