More than likely the unidentified rider was only another drifter.
The Euphrates was crossed at Birejil (Til Barsip ?), or Jerablus (Carchemish?), or Tell Ahmar (unidentified), or Thapsacus.
Public knowledge noted the arrest resulted from yet another unidentified tip.
Most cheerleaders also go unidentified by the vast majority of sports attendees.
The casket has the mark of an unidentified Parisian goldsmith of the 15th century.