The crime: Serial killer Fritz Honka killed four women in Hamburg

The guest: Sylvia Lundschien, Inforadio journalist

A simple google brings more information about Friedrich Paul "Fritz" Honka than you could ever need. 

Here's his wikipedia page. His life was the basis for the (German) book Goldene Handschuh by performer Heinz Strunk (Amazon affiliate link) and the (German) film of the same name by Fatih Akin (Amazon affiliate link).

A report on his conviction that includes video of him entering the courtroom.