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I'm sorry to hear about your situation. Because the police are investigating, there's no open court case yet. You see, the police will conduct an investigation, and will either refer the matter up to the prosecutor or not. If not, then it's essentially dropping the case. If they do, the prosecutor then brings the citation before the grand jury or directly to court. But it doesn't sound like this has happened yet. As such, there's no court to file any motion for. Even if you were to file a motion, the judge wouldn't get involved in an ongoing police investigation unless there was clear evidence that there was some sort of collusion or other bias against you. Even then it's something that the judge would more likely than not "wait and see" what happens.
As such, anything that is going to be done at this point prior to the citation is "pre-court" and would need to be done through the police. You can contact the police, tell them that you're willing to cooperate, make statements, etc... and that you want to speak with someone about this accusation. Note that they have no obligation to actually take your statement, because the only obligation is that they have a belief and evidence that by a preponderance of the evidence this actually occurred. That's lower than the criminal "beyond a reasonable doubt" standard. If they believe that it's more likely than not that it happened as the accusation said it did, then they can refer it on to the prosecutor. But most of the time I find that they're still willing to talk with you about it and get your side of the story.
Hope that clears things up a bit. If you have any other questions, please let me know. If not, and you have not yet, please rate my answer AND press the "submit" button, if applicable. Please note that I don't get any credit for the time and effort that I spent on this answer unless and until you rate it positively (3 or more stars). Look for the stars on your screen (★★★★★). Thank you, ***** ***** luck to you!