“DNA was used to prove that the hair was not Tribble’s.”
Tests which could deal with this small a quantity of DNA didn’t come on the scene until much later than the trial. What had been done, sounds like the old “science,” such as it was, of hair characteristics. Today, per USSC, testimony based on science has to be based on the best science available to man. Except for one method of identification: fingerprinting. The old methods are still grandfathered in: a fingerprint expert either declares a match or non-match, rather than a likelihood of match. For now.