In your question, you reference matters that sound both criminal in nature and civil. Assuming the case is civil, the answer to your question is as follows: (1) The term "ex parte" essentially means that one party addresses the court without the other party present. Ex parte communications are generally prohibited except in situations that may be an emergency. If the court does grant ex parte relief, it typically does so only for a very short period of time (10 days or less) and follows up with another hearing on the request with both parties present. In other words, I do not believe that an "ex parte" motion fits into your scenario. (2) Only clerks of court or licensed attorneys can sign a subpoena (for documents, appearance for depositions, and attendance of witnesses at trial) in civil court. Therefore, the clerk of court will have to sign your subpoena. You will have to fill it out and ask the court to sign it. They will not put in the date or time for you; you pick it but you must give amble notice (at least 10 days) of the date for compliance. Additionally, you will be responsible for arranging for the court reporter (and paying the reporter's appearance fee). You also are responsible for giving the witness payment for their mileage and attendance. Frankly, I would not consider conducting a deposition yourself. There is a lot more to taking a deposition including the deposition's proper scope, the type of objections that can be made (or not), and other matters that are not common knowledge. I strongly encourage you to hire a lawyer.
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