Tennessee Code Title 32. Wills § 32-2-104

(a) Written wills with witnesses, when not contested, shall be proved by at least one of the subscribing witnesses, if living. Every last will and testament, written or nuncupative, when contested, shall be proved by all the living witnesses, if to be found, and by such other persons as may be produced to support it.

(b) Upon petition of any interested party, the court, in its discretion, may permit the proof of any subscribing witness who is outside of the state or county or who is unable to testify in person, to be taken by interrogatories or deposition in the same manner as provided in chancery cases. For the purpose of taking interrogatories or depositions a photostatic copy of the original will may be furnished to the witness, or in the discretion of the court, the original will may be withdrawn and used in the manner prescribed by § 32-2-103.