Sex offender was registered in a small local municipality. During a recent sex offender check it was learned that he has never lived at the listed address. Instead he lives in Dallas. He just used his elderly aunt's address for registration. Can I prosecute it in my county or does it have to go to Dallas.

Either aunt's county or Dallas is proper. Look at TCCP 13.31 - Venue would be proper in the county where an element occurred, where he last registered or verified, where he inicated that he was goint to reside and was required to register, where he was put under custodial arrest for a subsequent offense, or where he resides or is found by a peace officer.