This is evidence that does not forget. It is not confused by the excitement of the moment. It is not absent because human witnesses are. It is factual evidence. Physical evidence cannot be wrong; it cannot perjure itself; it cannot be wholly absent. Only its interpretation can err.
Oath definition, a solemn appeal to a deity, or to some revered person or thing, to witness one's determination to speak the truth, to keep a promise, etc.: to testify upon oath. See more. Dictionary.com
Oath, [N] [E] The principle on which an oath is held to be binding is incidentally laid down in ( Hebrews 6:16 ) viz. as an ultimate appeal to divine authority to ratify an assertion. On the same principle, that oath has always been held most binding which appealed to the highest authority, as regards both individuals and communities.