discovered in the stasi archive in berlin by photographer arwed messmer .
show how secret police forced people trying to escape to re-enact method .
include pictures of primitive floats , children concealed in cars and tunnels .
secret police used the pictures for training and for use at trials as evidence .
have now been compiled in a book called reenactment mfs .
reenactment mfs by arwed messmer , is published by hatje cantz .