Witch's Game Mini - by Submachine

[Linkcat]

Your colleague set a trap inside the room after you left, then someone reached through the window and pushed him into the trap which killed him.

Your colleague set a trap inside the room after you left, then someone activated the trap from outside of the room which then killed your colleague.

[Submachine]

The key never left the keyhole. The witch pushed the key through the keyhole onto a newspaper lying below. Then pulled that under the door, and unlocked the door. He entered the room and killed the victim. The door can be set to lock while it was open, so the witch did so, left the key in the room, and closed the door, leaving the door locked.

The door can only be locked with a key, and only while it is closed.

Your colleague set a trap inside the room after you left, then someone reached through the window and pushed him into the trap which killed him.

Your colleague set a trap inside the room after you left, then someone activated the trap from outside of the room which then killed your colleague.

Your colleague didn't set traps.

[dawn to dusk]

The victim and the culprit killed each other

[Submachine]

The victim and the culprit killed each other

Blue Truth incomplete (how did the culprit kill the victim?). Also, I would like to refer back to my question to Fippe.

About only one person dying, I am willing to give you this truth, but I don't see how this furthers your investigation. Wouldn't this just make the list of Red Truths longer and more difficult to check?

[dawn to dusk]

The victim and the culprit killed each other

by stabbing each other to death.

This removes the "There were no living people when you entered the room" ambiguity

[Submachine]

Very well.

Only one person died during the story.

[Linkcat]

Someone placed a lethal device in the room through the window, then triggered the device which killed your colleague.

[Submachine]

Someone placed a lethal device in the room through the window, then triggered the device which killed your colleague.

I extend a previous Red Truth for this one.

A culprit could only use a weapon or a trap from inside the room.

[Linkcat]

Your colleague died due to something accidentally falling and killing him or any other accident that was outside of his control.

[Submachine]

Your colleague died due to something accidentally falling and killing him or any other accident that was outside of his control.

Your colleague would not suffer an accident on his own.

[Linkcat]

Your colleague unlocked the door, then someone entered, killed him, locked the door from the inside, then hid under the floorboards or in the ceiling.

Your colleague leaned out the window, then someone grabbed him and cut his throat with their fingernails and he fell back into the room.

Your colleague leaned out the window, then someone grabbed him and repeatedly smashed his head against the side of the window and he fell back into the room.

Someone broke the window, your colleague leaned out the broken window, then someone grabbed him and cut his throat on the broken glass and he fell back into the room.

[Submachine]

Your colleague unlocked the door, then someone entered, killed him, locked the door from the inside, then hid under the floorboards or in the ceiling.

Your colleague leaned out the window, then someone grabbed him and cut his throat with their fingernails and he fell back into the room.

Your colleague leaned out the window, then someone grabbed him and repeatedly smashed his head against the side of the window and he fell back into the room.

Someone broke the window, your colleague leaned out the broken window, then someone grabbed him and cut his throat on the broken glass and he fell back into the room.

Noone was hiding in the room when you found your colleague.
Technically, to hide anywhere that is not in the room, the person must exit the room first. But:
Only the door and a window can exist as entrances and exits to the room.
Both the door and the window lead outside.

Your colleague was not attacked with a close-ranged method through the window.

To simplify or clarify what could or could not happen, you can ask me to repeat something in red.