A recent property-tax bill or notice, lien or mortgage statement, payoff letter, creditor or court paper, parcel number, or tax-sale notice can help. Start with the property address if that is all you have; you can call before the paperwork is complete.
The creditor or tax office named on a notice confirms its current balance, status, and instructions. The Knox County Register of Deeds handles recorded-document questions; the title company checks the records and confirms what applies to the proposed sale. An Assessor record is for assessment and parcel information, not a current payoff amount.