Riddles [COMPILATIONS]

SUICIDE OR NOT?

A dead female body lies at the bottom of a multistory building. It looks as though she committed suicide by jumping from one of the floors.

When the detective arrives, he goes to the first floor of the building, opens the closed window, and flips a coin towards the floor. He goes to the second floor and does the exact same thing. He continues to do this until he gets to the top floor of the building.

When he comes back down, he states that it was a murder and not a suicide. How does he know that?

ANSWER??