In Delk v. State, 590 S.W.2d 435, 440 (Tenn. 1979), the Court held that a party may comment about an absent witness when the evidence shows as follows: (1) the witness had knowledge of material facts; (2) that a relationship exists between the witness and the party that would naturally incline the witness to favor the party; and (3) that the missing witness was available to the process of the trial court.