Jenseits der Spree S02E05 - Mutterliebe

Petra Berger is found dead at her dining room table - bound and gagged. In front of her are a pot of tea, a moldy sandwich and a withered apple. Inspectors Heffler and Neumann also discover that the house was pelted with paint bombs. The victim's hair is smeared with red paint. A ritual murder? Robert realizes that an example has been made here. But why?