One of three core members of the National Socialist Underground, Mundlos operated underground for over a decade as part of a cell that carried out racially motivated killings and bombings largely without detection by German authorities. The group's ability to evade law enforcement for so long — and the institutional failures that allowed it — made the NSU case one of the most significant domestic terrorism scandals in postwar German history.

His confirmed victims — seven young women killed across the southeastern United States over roughly six years — represent only what investigators could prove, as German authorities have long suspected additional killings dating back to his Army posting abroad in the early 1990s. The possibility that his crimes began overseas and continued undetected for over a decade underscores how geography and institutional context can obscure a pattern of violence until it reaches a threshold investigators cannot ignore.

A U.S.-born figure who rose through Mexico's cartel underworld to become one of its more operationally brutal commanders, Valdez is notable both for his unlikely background and for the methods he used to wage an internal power struggle that left over 150 dead following the 2009 collapse of the Beltrán Leyva leadership. His use of videotaped torture and decapitation was calculated as much for psychological effect as for physical elimination of rivals. The gang infrastructure he built dissolved within a year of his arrest.