Conversation so far:
What was Erich Mielke's trial about?
The trial was about Erich Mielke's involvement in a murder.
Who was Erich Mielke accused of murdering?
Erich Mielke was accused of murdering Captain Franz Lenck.

Question: what was the motive behind the killings
Self-contained rewrite: What was the motive behind Erich Mielke killing Captain Franz Lenck?