They are seeking 'retribution for' the killings.
The killer acted without fear of 'retribution'.
(..) Capitol officials, peacekeepers, torturers, Gamemakers. But the danger is, once we begin, the rebels will not stop calling for retribution. Thirst for blood is a difficult urge to satisfy. So I offer an alternative plan. Majority of four may approve it. No one may abstain. (..)2015 The Hunger Games: Mockingjay - Part 2