In her essay "Gestern Morgen", Bini Adamczak tells a story from Manes Sperbers "Wie eine Träne im Ozean." I'll paraphrase:
In 1935, a member of the German Communist Party (KPD) finds himself doubting the strategy and analysis of the party in its dealing with the Nazis. He starts meeting and talking to dissident communists and even members of the SPD. Because a formal exclusion from the party is difficult to achieve, as the KPD is already illegal, his seniors in the party find a 'pragmatic' solution and rat him to the Gestapo. The party member gets imprisoned in a concentration camp, where he is treated as a traitor by his fellow communists.
Now, this is taken from a novel. I understand that Sperber wanted to expose a certain modes of thinking within the party, such as obedience and compliance, that certainly existed. And we know that Stalin delivered German communists into the hand of the Nazis.
But are there any accounts of the German KPD actually ratting out its comrades to the Nazis as a way of dealing with dissidents?