Comment by thinkingemote

Perhaps for the same reason Russia's intelligence forces does it? They kill people in an obvious manner to send a message and the message is to demoralise, destabilise and psychologically harass other people. "I could be next"

I'm not sure if the Stasi disappeared people in an obvious or hidden manner though. Maybe they did it more frequently than modern states assassinations? In both cases it shows that the life of any person is not important to them - what's important is the effects an action causes.