Daniels was formerly involved in Treadstone, where he worked as a recruiter. He recruited Jason Bourne, then known as David Webb, in Operation Treadstone in 1997, and was present when Albert Hirsch was breaking down Webb in order to break his will to become an operative.
Sometime before or after Treadstone, he was reassigned as a station chief in Madrid, Spain, and at the time of Bourne Ultimatum acts as the primary source for Guardian journalist Simon Ross. He is later killed by an explosion set up by Desh Bouksani.
Daniels' first name is spelled both 'Neil' and 'Neal' in different places in the movie.