A friend of my German father-in-law spent five years in a STASI prison for having the audacity to decline the two jobs offered his class the year he graduated - barber or baker.
He wanted to be a dentist. After he was included in a prisoner swap at the Glienicke bridge, he was able to finally realize his dream and become a dentist.
According to some here the Stasi were merely collecting information like a census taker, certainly not undertakers - they got a bad rep evidently. Information collectors by definition don’t take prisoners certainly, at least it seems for some.
Sorry your Dad had to go through all that - it was a very rough time for a lot of people. But in the end he was finally able to realize his dream, a good thing for anyone.