Damien was killed in one of the carts and the culprit left him there. When the train shook, luggages or other items fell on his body, that's why noone found it.
I feel like Damien's death is the most ambiguous, so let me add this piece of story in:
The officers listened to your story carefully, but took note of something.
"...and then after reaching the top of the stairs, you entered the driver's cart where you saw the three corpses of the train staff and ran off immediately due to fear and to find help possibly?"You claim yes and told them that's what you last saw before running off. Out of caution, one of the officers boldly decided to enter the train of the 2nd cart (the door had been opened as the train was stopped), and took a peek around. As the group watched the officer take a pause after turning to the bathroom, the officer then carefully stepped up to the top floor of the 2nd cart... only to come down back with a tense face.
"...are you sure it was three?" The officer asked.
"I'm pretty sure it was three, my vision isn't blurry-""I just counted four. There was a non-train staff person in that same cart who has apparently bled to death. Probably no older than 22.""Are you talking about the black guy?"Everyone besides you had turned to Leo at the point. The officer gave an eyebrow.
"...yes, he was black. And he was wearing a hoodie."You didn't realize six people were dead until this point. How did a corpse magically appear there?
Damien's body is now found in the Driver's cart! However, how did his body even end up there without teleportation magic if you saw all there was in the Driver's cart?
Damien's body was never obscured by luggage.
