This outlines the sources used for the data summarized on this site.
Where "Media reports" are mentioned, you can find links to them on the relevant counter's page: click the Info icon next to the counter (or on any node in tree view), then Explore the data.
The four-year attenuation window used by every USAID counter's culpability model, and the staircase schedule used by the two AIDS counters, derive from the published PEPFAR transition plan: