On 19 May 2018 the New York Post reported that multiple outlets had named Stefan Halper, then 73, as the secret informant who met Carter Page and George Papadopoulos starting in summer 2016. Breitbart (21 May 2018) ran a “who is” piece and repeated the campaign-infiltration slogan as a question, not as a court caption. Daily Caller had already been on the contacts.
The Conservative Treehouse (19–20 May 2018) treated the naming as a leak with a defensive narrative. That is commentary. Epoch Times later returned to the same identification when covering a Senate subpoena. RealClearPolitics republished a RealClearInvestigations feature on Halper’s Pentagon wages (July 2019). No original RealClearPolitics investigation unique to this file was located beyond that RCI piece.
Naming by newspapers is not an OIG caption. When Horowitz published in December 2019, the printed label was still Source 2. Keep those layers apart.