"...the police press "play" and listen to it..."
"...-''my life is a mess,I can't take it'' then they hear a gunshot"
The policeman must have asked himself who had turned off the tape recorder
than?
1/0 or 0/0 or some other forms are meaningless without specification of their origins (functions).These,generally written as here, are not numbers and sign "=" becomes meaningless for comparations.