Nephi then delivers the coup de grace by instructing the messengers to examine Seantum’s cloak where they will find traces of blood on the edges. This detail relies on Seantum’s wearing the same garment in which he committed the murder. Most people in the ancient world had few clothes available to them and concepts of cleanliness were defined very differently. Surely had there been massive bloodstains, the cloak would have been changed, but these were apparently not immediately noticeable, requiring specific examination rather than a cursory glance.
If Seantum had not already been rattled by his own guilt and the obvious suspicions of his interrogators, he might have created a plausible account that the blood belonged to some animal he had butchered or some other excuse. At that time, no one would have been able to tell the difference. However, overcome by guilt, he confesses.
This confession confirms Nephi’s prediction to the last detail, absolutely clears him of the judges’ accusations, and validates his claims to have divine access to otherwise unavailable knowledge—including the prophesied future destruction. Nephi was not concerned about clearing his name but of providing unshakable evidence that he is Yahweh’s prophet.