For the Zersetzung of groups, it infiltrated them with unofficial collaborators, sometimes minors.  The work of opposition groups was hindered by permanent counter-propositions and discord on the part of unofficial collaborators when making decisions.  To sow mistrust within the group, the Stasi made believe that certain members were unofficial collaborators; moreover by spreading rumors and manipulated photos,  the Stasi feigned indiscretions with unofficial collaborators, or placed members of targeted groups in administrative posts to make believe that this was a reward for the activity of an unofficial collaborator.  They even aroused suspicions regarding certain members of the group by assigning privileges, such as housing or a personal car.  Moreover, the imprisonment of only certain members of the group gave birth to suspicions. 
But Götz had no regrets and went on to win the UEFA Cup in 1988 with his new West German team, Bayer Leverkusen. But life in the West did not mean he, or others, had escaped the clutches of the Stasi (indeed, he later found out that the Stasi had, within their files, photographs of his new home in West Germany). Cases of defectors drugged and smuggled back East, although rare, were not unheard of. A friend of Götz in West Germany, a fellow East German, was killed in a car accident. Götz, suspecting it was no accident, feared for his own life.