Okay...
*takes a deep breath*
...
..
WHAT THE FUCK?
X_x
So for now we know that there were "guards" put there by Hitler, but at the time mysterious person knocked on door, they were somehow asleep.
When they opened up, that mysterious person "ran away" with the body X_x"
And then we get a timeskip AGAIN O_o"
Chess? X_x'
WTF?....
hiatus O_o"
I am betting that something will happen when they return to order, making Allen traitor etc...
WTF?
T_T'
*goes off to take the pieces of his shattered mind*
EDIT:
anyway its clear that cross is gone. "no one saw him again", pretty much means that. I bet one day Allen will hear from Hitler or someone on what happened to Cross body and etc. "no one saw him again" is usual "complete future" type sentence (like in Eizenhorn trilogy "last time I saw him").
So Cross is as good as death, but someone hiding in the room or something wanted his body for some reason.