Jack Walters was one of Daniel Reynolds' superiors. The Assistant Deputy Director of the Westchester FBI field office. He provided multiple resources to Reynolds to assist in arresting Atticus Nevins. He seemed to be very fixated on Abbie Mills and Ichabod Crane. Walters had Reynolds inform him of Abbie's behavior on a regular basis.
Walters calls Reynolds to persuade him to use minimal resources in tracking Nevins and heard that Abbie was not the same agent she used to be before she went missing. He is seen sitting next to Nevins in his car. Walters hired him to receive August Corbin's very first case file which contains what Nevins called "The exact coordinates of the nine sacred sites." Earlier, Nevins mentioned that Corbin discovered and identified dozens of crypts and tombs like the cave in Iraq which contain multiple ancient artifacts with supernatural and historical significance and creatures with connections to these artifacts. Corbin may have discovered the coordinates of these nine sacred sites and seemed to have discovered that they had something dangerous in common and hid the files to protect their secrets and locations. Walters discovered that Corbin had the coordinates and sent Nevins to retrieve the case folder. After he received his case files and paid Nevins for his services, Walters shoots Nevins in the head in his car to wipe the trail clean. 
Reynolds tells Sophie Foster about how Walters wanted him to report to him about Abbie's behavior. They both came to the conclusion that Walters is focusing on Abbie so much because of her role as one of the Witnesses. 
Walters is revealed to be a member of Agency 355; a secret society which battles supernatural forces which was founded by George Washington in 1789. Washington appointed Ichabod Crane as the leader of the society. Ezra Mills knew about this organization and warned Ichabod that there are many members who lost their way. Whether Walters lost his way or not is indeterminate at this point. He and a few other agents escorted Ichabod to Washington D.C. since Walters told him that there are some people who want to speak with him. Ichabod insisted on going with him since Walters told him that it was his choice. 
|"I, Witness"||"Whispers in the Dark"||"Blood and Fear"||"The Sisters Mills"||"Dead Men Tell No Tales"|
|"This Red Lady from Caribee"||"The Art of War"||"Novus Ordo Seclorum"||"One Life"||"Incident At Stone Manor"|
|"Kindred Spirits"||"Sins of the Father"||"Dark Mirror"||"Into the Wild"||"Incommunicado"|
|"Dawn's Early Light"||"Delaware"||"Ragnarok"|