King Aelfred, The Father, is the Grand Maegester of the Order of the Ancients.
During a cutscene, Aelfred gives you the final Order medallion and reveals his original goal to destroy The Order from within.
This leads you to finding King Aelfred as the informant instead.
Once you’ve taken out every single Order member, including the Zealots, Hytham will mention having an informant with information about who The Father is.