Troll was never a Nazi, opposing the regime instead, but a number of factors have been cited for his betrayal, among them financial difficulties, his treatment while being held at Dachau and the threat of physical violence against his stepbrothers should he not cooperate.
Troll worked as a labourer on building sites and as a life guard for the city of Munich, but lost his job in 1931 because of his left-wing activities and thereafter remained unemployed until 1934.
The possibility exists that he either already worked as an informer when he joined the KPD in 1932,[3] or that he may have been forced into cooperating after his release by the threat that his brothers would be killed or ill-treated at Dachau should he refuse.
Those as well as communists who distributed illegal leaflets and collected donations for the Rote Hilfe, an organisation supporting family members of people arrested by the Nazis, were betrayed by Troll.
Troll travelled repeatedly to Switzerland and Czechoslovakia to obtain donations and instructions while also infiltrating the non-communist resistance in Bavaria with his informers.
[3][7] Because of his work the Bavarian political police were able to wait until mid-1935 until initiating a wave of arrests,[3] being in almost complete control of the communist resistance in Munich and able to direct it through Troll.
The sentence against Troll in Regensburg was one of the hardest for Nazi crimes there and also included confiscation of his assets, loss of the right to vote, and a ban from working.