As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SHIP 9585 -ATB/SMKE/DE- THE CREW RETURNED THE FLIGHT BACK TO SDF DUE TO VISIBLE SMOKE AND ODOR IN THE MAIN CABIN. CORRECTIVE ACTION: MAINTENANCE ISOLATED THE SOURCE TO THE LEFT PACK SYSTEM WITH APU OR ENGINE AIR. PLACED LEFT PACK ON MEL. (LP #6779456)