A man entered his house and was about to hang up his coat when he heard his wife shout;
"No John! Don’t do it!"
There was a shot and he could hear his wife fall down. When he entered the kitchen he saw his wife and the gun lying on the floor. There was a police officer, a doctor, and a lawyer standing next to her. Peter immediately knew that the police officer had shot her.
But how did he come to know?