In addition to what you wrote: http://en.wikipedia.org/wiki/Border_guards_of_the_inner_German_border
As a further measure to prevent escapes, the patrol patterns of the Grenztruppen were carefully arranged to reduce any chance of a border guard defecting. Patrols, watchtowers and observation posts were always manned by two or three soldiers at a time. They were not allowed to go out of each other's sight in any circumstances. When changing the guard in watchtowers, they were under orders to enter and exit the buildings in such a way that there were never fewer than two people on the ground. Duty rosters were organised to prevent friends and roommates being assigned to the same patrols. The pairings were switched (though not randomly) to ensure that the same people did not repeatedly carry out duty together. Individual border guards did not know until the start of their shift with whom they would be working that day. If a guard attempted to escape, his colleagues were under instructions to shoot him without hesitation or prior warning.