Crime Time: On the Trail of a Chainsaw Killer

Prosecutors, forensic scientists, police officers and profilers describe the cases that they won't forget any time soon. How do you manage to convict the perpetrators? What makes real killers tick?

Self-defence, murder or a bad joke? These are the questions that the police ask themselves when a mysterious letter arrives in June 2018. In it, Tanja B. writes that she stabbed her partner to death a week earlier and then cut him up with a chainsaw - in self-defence. 90 minutes later, a policewoman opens the apartment door and makes a horrific discovery: In the bathroom, wrapped in garbage bags, lies the dismembered body of the bus driver, Martin F. The extensive investigation starts immediately. Is it really self-defence or is it murder?