Short answer is no they do not have to start over. Any evidence obtained by the government can be used in other cases. There is an argument that the evidence could be "fruits of a poisonous tree" and be inadmissible. The accused needs to hire an criminal defense attorney ASAP so they can start preparing for defenses and trial.
"Nothing in this communication is meant to establish an attorney-client relationship. The information is provided for educational purposes only. No action will be taken on your behalf unless you have have hired me and entered into a written retainer agreement. I am only licensed in Tennessee and I suggest contacting an attorney in your specific city and state as soon as possible to avoid any statute of limitations deadlines, if applicable."
If they filed in wrong county, they have to dismiss and defile. No problem with using evidence from another county.
Claiborne H. Ferguson, Esq. is * Certified as a Specialist in Criminal Trial Advocacy by the National Board of Trial Advocacy. * Certified as a Specialist in Criminal Trial Advocacy by the Tennessee Commission on Continuing Legal Education and Specialization.