Scene of the Crime — Episode 27: Missing

You are watching the episode Missing Lena Odenthal gets a call: a witness wants to testify something important about a murder, but when Lena Odenthal arrives at the meeting point, the witness is dead. The case she wanted to testify about was twelve years ago, the murderer confessed and has served his sentence. So what else did Michaela Bäuerle want to share?