Stein brought in Gary Washington (Knight One) and Black Thorn as Checkmate operatives, both of whom were his friends, and both of whom were introduced during his run on Vigilante. Checkmate! was at various times involved with the other government agencies in the DC Comics universe, primarily the Suicide Squad, which resulted in the crossover "The Janus Directive". Checkmate! was canceled after 33 issues but the organization continued to appear, mostly in titles related to either the government or Batman.