A boy was found dead by his friend Jason. The police arrived after the Jason called the police. Jason was asked how he found the boy, so Jason responded: "I was out taking a jog when I came to his house. I decided to stop by and say hi. I looked through a window and as frost being on the glass, I wiped away the frost to see inside. As I looked I say him lying here on the ground with a pool of blood around him and I there upon decided to go into the house. The front door-". But after hearing this the police decided they had heard enough and arrested Jason. How did they know he was lying?