A 32-year-old man is found hanging from a ceiling fan in his locked bedroom by his wife. The body is brought to the mortuary for autopsy. On external examination, there is a ligature mark on the neck that is oblique, running upward toward the angle of the jaw, with the knot positioned at the back of the neck. The mark is not continuous around the neck. There is facial congestion, petechial hemorrhages in the conjunctivae, and a frothy fluid at the mouth and nostrils. What is the most characteristic feature of this hanging that distinguishes it from strangulation?