Dark Room Hunt
Five contestants are placed in the \(5\times 5\) square dark rooms for the Dark Room Hunt: Ben, Elaine, Josh, Max, and Rose. Each room is conjoined to other rooms with at most 4 doors at all sides (no diagonal connection), and each person can move vertically or horizontally one room at a time but can't retrace or resume their step immediately (For example, after going upward, he or she must turn left or right and can't reverse downward or keep going upward immediately).
The diagram on the left shows the starting points of the five players. After 7 moves, the lights are back on, and Rose is found dead in the central room with the others at the positions on the right. During the game, the paths are so dark that nobody sees who is ahead or behind themselves. The only time two persons bumped into each other was when Rose opened the same door with the killer, who pushed her back and murdered her in the central room before fleeing the crime scene. No-one else had a chance to meet any other person or pass Rose's body after the murder.
Who is the killer?