If anyone wants to catch up, then I’m pretty sure I’ve collected all the non redundant reds surrounding E’s death here:
#On the topic of Doors
E and D’s room doors both have only one key that can open their locks. For the purposes of this mystery, nothing other than a key can open a lock, other than forcing the door open, irreparably breaking the lock.
A door can only be locked when it is closed.
In the case of the first two deaths, only one key was found inside each room, and was found in a tray. In addition in both cases this key was the sole key to the sole door that entered the room, and was not moved from when the door was broken until it was discovered in the tray.
With the proper key, a door can be locked from either the inside or the outside.
I’m afraid the key on the tray beside E’s bed was the key to E’s room.
In both cases, the key was already on the tray when the rooms were broken into.
the teacups are very light, and the keys are rather sturdy. Such an attempt [Blackrune’s teacup trick] would certainly have tipped over an empty teacup, and in both cases, the teacups were empty and upright on the nightstand tray.
Other than the gap between the door and the floor, there are no gaps through which keys could pass through.
Not once during the weekend did a key travel into a room from under a locked door.
#On the topic of other extrances
Windows can only be locked from the inside. If a window is locked, it cannot be opened without breaking the window. Both of the times in the narrative when B broke into a murder scene, the windows were locked. Excluding the window B broke to get into D’s room, the windows of D and E’s room were unbroken when B broke into those rooms as described in the narrative. No exits or entries other than doors or windows are relevant for this mystery.
The windows of E’s room were already locked when B forced open the door.
The same applies for windows, they can only be locked when closed.
#Matters surrounding the death itself
Neither C nor E committed suicide.
E’s death was not accidental or a coincidence. He was murdered.
E was dead before B broke into the room.
E had not sustained any injuries before locking the door to his room for the final time.
the bit about it being impossible to stab someone in the heart through the gap under the door was objective narrative, and thus truth.
#About B’s declaration of E’s death, along with the cirucumstances of the discovery
B shouted that E was dead almost immediately upon entering the room, and C and D entered the room almost immediately after B’s shout. B had no more than 5 seconds of unsupervised time inside the room. Five seconds is not enough to get rid of all traces of a trap that stabs/shoots a man to death.
he [B] was not trying to make anyone believe E was dead when he really wasn’t.
If B at any point thought one of the other three was dead, he certainly retained that view until the end of the story.
If B didn’t believe E was dead, his exclamation about E’s death was not meant to make C and D believe E is dead.
#Miscellaneous points
There is no person “A”, or any other fifth person in addition to those referred to as “B”, “C”, “D” and “E”
no supernatural elements such as ghosts are involved in this mystery.
In addition, very recently @Blackrune managed to propose a way around B’s confusing exclamation:
Time to begin this gameboard’s requiem!
E was stabbed through the heart by someone who left via the window! The door was locked at this point in time, along with the key to the room’s door being on the tray. E then locked the window after his assailent left and then he died sometime after as a result of the wound.