A homicide detective is called at a crime scene. A man is lying dead in front of the building and seeking the position of the windows on the building and the position in which the body is lying, it is evident that the man jumped out from one of them and committed suicide.
The detective asks his team to collect the traces if they can find any on the body and heads towards the building. He goes to the first floor and towards the room that is on the front side. Inside the room, he lights a cigarette, walks towards the window facing the dead body, opens the window and throws out the cigarette. He then goes to the second floor and repeats the same process.
He keeps doing the same thing till he is done with all the floors and then takes the lift to the ground floor. Upon reaching there, he informs the team that it is not a suicide but a murder.
While the whole team is shocked to hear the revelation, he lights another cigarette and takes a hard puff.
How do you think he found out that it was a not a suicide?