Tenn. Code Ann. § 66-23-115

If the person executing the instrument is dead, or resides or is beyond the limits of the United States and its territories, and the subscribing witnesses are dead, or have become insane or blind, or deaf and dumb, since they became subscribing witnesses, or they cannot be found, then the instrument may be proven for registration before any of the officers mentioned in § 66-23-101, by any two (2) persons acquainted with the handwriting of such maker or such witnesses.