Criminal Law Questions? Ask a Criminal Lawyer.
I am a licensed attorney and former prosecutor (4 years). I am familiar with assault cases, and I will be happy to assist you with your question.
If charges have already been filed, the matter is out of the arresting officer's hands. The prosecuting attorney (also known as DA) is now in charge of the case. He/she can ask the judge to dismiss the case, but, that likely won't happen unless the victim either agrees or initiates the request for a dismissal. You aren't permitted to bully or threaten the victim into agreeing to or requesting a dismissal, but, if you are currently on good terms with him/her, you can always ask him/her if requesting a dismissal would be a possibility.
Another way that the case could be dismissed is if the victim doesn't appear for trial, but, I wouldn't rely on that happening, particularly if there are other witnesses to the incident.
Hope this helps, and good luck.
Ask the victim to contact the prosecutor's (DA) office ASAP and state that he/she no longer wants to cooperate with the prosecution of this case and wants to request a dismissal. The prosecutor's office will take it from there and file the necessary paperwork with the court.
I don't know how long it will take for your local prosecutor (DA, city attorney) to drop the charges. All prosecutors offices operate on their own particular time frame. When I was a prosecutor, every Friday afternoon, we would interview victims (domestic violence, assault, etc.) who wanted to request dismissals. Our secretary would do the necessary paperwork the following Monday morning, and then it would get filed with the court shortly thereafter. Depending on the judge's schedule, it would take him anywhere from several hours to several days to sign the dismissal and make it final. Of course, this is just an example -- this may not be the time frame on which your local prosecutor works. However, I really don't think it should take too long. Your goal is simply to have it dismissed before it goes to trial.