Logic Riddles

Question: What is in the middle of a human?

Question: How do you make 9 by just 3 toothpicks?

Question: I start at the beginning and I finish at the end I fly through the middle and I return again.

Question: When you don't have me, you want me, but when you do have me, you want to give me away. What am I?

Question: A police officer was walking outside of a diner. He heard somebody yell inside the diner "No, John not the gun," followed by a gun shot. The officer immediately ran inside and found a milkman, a doctor, a lawyer, and the dead body. The cop immediately arrested the milkman.

How did the officer know the milkman man did it?