I'm not too sure about that; Colorado may be a state where they don't need her to press the charges.
One thing I have thought was that the DA got into this case and filed the charges because the sheriff jumped the gun on arresting Bryant without consulting his office.
I do know that I heard that a lot of the attorneys that were in the courtroom were shocked that this is all his has; and evidently so was the judge, as written in his ruling sending Kobe to trial.