A St. Louis dentist who used his professional respectability as cover, Engleman carried out a series of murders-for-hire spanning roughly two decades, often targeting victims whose deaths would yield insurance payouts to co-conspirators. The combination of a legitimate career, military background, and calculated financial motive made him a difficult target for investigators until patterns across the killings eventually drew scrutiny. He was ultimately convicted of multiple murders and died in prison.

Among the architects of organized drug trafficking in Mexico, he stands out for a career that began inside the state security apparatus before pivoting to build the criminal infrastructure that would eventually become the Sinaloa Cartel. His trajectory — from federal police officer to cartel co-founder — illustrates how institutional access and relationships shaped the early structure of Mexican narco-trafficking. The organizations he helped establish became central to the movement of narcotics into the United States over several decades.

Active during the height of the Depression-era outlaw wave, Floyd became one of the most publicized bank robbers of his time — a figure whose notoriety was shaped as much by media coverage as by the crimes themselves. His relatively brief career nonetheless placed him among the cohort of gangsters — alongside Dillinger and Barker — that the newly empowered FBI made its primary targets. The gap between his public image and the violence of his record illustrates how the press of the 1930s could turn wanted men into complicated folk symbols.