I watched the finnish Police TV and this is true. One guy had decided to kill someone and he looked from Facebook a girl and after some conversation they decided to meet. They met in the girls home, her best friend lived next door and they had skype on when the guy came. The skype was for safety. So the friend saw how the guy attacked after a while to the girl, her friend called the police and they came very fast.
The guy had left already but still the police found him sitting in his car and the adrenalin flowing so that he didn't understand to run. He had sent to his friend"I did it!"