The Fury Wraith
I want some reds and by darn I'm gonna get some.
The cabins of the ferris wheel's windows can actually be opened and Beowulf simply escaped through the window of the cabin. There is mention of the window at the control panel that cannot be opened and the window of the apartment being locked from the inside, but there is nothing mentioned about the windows of any of the ferris wheel cabins other than that they simply weren't broken. The gameboard never directly adresses that escape through the cabin window is impossible. Just that the windows were never broken.
Alternatively, the cabins themselves could simply not be enclosed from all sides. There might be an opening, such as on the roof of the cabin, part of the build-in design of the cabins that is difficult to reach and therefore escape through such an opening is never considered by anyone. Beowulf reached the opening by by slamming the sides of the cabin like DWaM suggests, making the cabin move around like a pendulum and so could reach the opening up top by making the cabin swing wildly enough.
As for the locked room that is Wolfgang's flat, for now I'm gonna be cheap and will just say that the culprit temporarily replaced the lock to the door and installed it back in after he was done in Wolfgang's flat. Like if it's a doorknob lock, just unscrew the doorknob and the culprit temporarily replaces it it with a doorknob he does have the key to. Unlock the door and do your business in the flat. Then when he is done, lock the door again replace this new doorknob with the old one that is compatable with Wolfgang's key. This doesn't count as damaging the door as the door itself remains intact and this doesn't count as picking the lock as you are removing the lock entirely.
The Fury Wraith
Gonna give it a try...
The victim was trying to hide in the Ferris Wheel from The Pack as to avoid getting caught by them because he stole their silver. Beforehand, the victim tampered with the lock of the cabin. Normally, you turn the bolt up, slide over, then bolt down to lock it. But the victim did something to the lock so that the bolt can’t go all the way down after you slide it over or it goes back up again shortly after turning the bolt down for the proper lock. (Piece of material placed to prevent the bolt from going down all the way, broke part of the lock or maybe the lock is old and worn so it didn’t close down properly to begin with.) The slide part of the bolt still works properly, however, so Wolfgang assumes he locked the cabin properly.
Of course since the slide part still works, the door to the cabin can’t be opened by this alone as that slide is still in place. But once the slide happens, the bolt is effectively off the lock and so can still open the door without having to slide it back down again, as is the case with all sliding bolt locks. This is where the trick comes in.
Before you can go to the top of the Ferris Wheel, it of course has to go in this crescent moon angle before you reach the top. (So if you’re in a cabin, you start all the way down, then it goes left, left up, up, right up and now you are at the top) This movement of going left and then left up, along with the velocity of the Ferris Wheel moving and perhaps some gravity, causes the bolt to slide to its unlocked state and the door can be opened from inside the cabin as a result.
Now back to the story. Geri and Freki arrive at the Ferris Wheel, having found Beowulf’s hiding spot because they need their silver back. The above paragraphs set up was done by Beowulf all in the case this would happen, as he knew he’d be sitting duck otherwise. But they were not going to get him alive, so time to commit suicide. Beowulf jumps out of the Ferris Wheel the moment Wolfgang and Freki are out of view, going towards the control panel. Beowulf dies. (The police say death was more or less instant and that the knife had pierced the victim's heart, but they never said death was due to the knife.)
At this point, Geri saw this happen and hatched a plan to keep the silver all for himself while pinning Beowulf’s death on Wolfgang. (Or perhaps this was his plan all along given the security footage, expecting that it was likely that Beowulf would kill himself if he was caught, or perhaps they were in cahoots all along. Might reconsider this later.)
Geri hides the body of Beowulf, by ordering his bloodhounds to all group together in a cozy herd and stand right near the body, (Kinda like a sheep herd except with dogs) making the body out of view as all the hounds are covering it like this:
(Except with hounds of course...)
However, one of the hounds decide to chew on the victim’s leg at this point, which causes a wound in the leg, which Geri later patches up with bandages)
When Geri and Freki bring Wolfgang to their hideout, they take the lead with the hounds only really following close behind them going after the humans. This way nobody ever notices the corpse that is lying around on the ground near the Ferris Wheel. The body is left behind there and since nobody is around thanks to the pandemic, it stays there for a while and is never found.
Geri and Freki beat the snot out of Wolfgang, perhaps even knocking him unconscious once in a while, back at the hideout. It is at this point that Geri obtains Wolfgang’s key to his flat, as well as his trinket which is found on top of the corpse later. (Would be easy to pickpocket Wolfgang during interrogation without him noticing because he is getting beat up) At some point during the interrogation, Geri goes back to the Ferris Wheel to collect the corpse, which he brings to Wolfgang’s flat, presumably near the window. Geri enters Wolfgang’s flat, opens the window to haul the body in and thrusts a dagger into the victim’s back.
For the chain lock, I assume there must have been a way to put the chain in place while still being on the side of the flat’s exit. Your hand can’t go through the gap of the door, but with a chain lock there is still a gap regardless. Perhaps by the use of some thin and long tool, like a pencil or something else that’s long and thin, Geri could scoop the chain through the gap of the door and then attempt to drop the chain to where the chain is supposed to go, into the lock. Repeat until successful. Geri locks the main flat door with Wolfgang’s key again and brings the key back to Wolfgang who is still in interrogation, who never notices his key was gone/back cause he was too busy getting beaten up to remember or notice.
As for Fenris and his surveillance camera… Fenris mentions he only heard the door open once, but he never said anything about hearing it close that would have prompted Fenris in checking the security footage. Alternatively, Fenris only checks the footage when he hears a door open and the culprit was super sneaky quiet with opening and closing doors to avoid detection by Fenris all other times. Fenris also only mentions he saw someone in the footage arrive AT THE APARTMENT and didn’t actually see anyone enter Wolfgang’s flat, all in all leaving plenty of opportunities to enter Wolfgang’s flat unseen and unnoticed. ...I guess.