When authorities believe a crime has been committed and make an arrest, charges are not always a guarantee. Before pressing charges, the police will write an arrest report and have it looked at by a prosecutor. The prosecutor will then make a judgment: should I send this case to a grand jury and let them decide what charges to file? Should I make charges formal without a grand jury or should I drop the case altogether?
It's important to understand that our criminal justice system is run by humans. Humans are subject to prejudice, preconceived notions and ulterior motives. In deciding whether to pursue a case or not, a prosecutor may have many things in mind: