Operating in the Russian city of Perm during the late 1990s, Malyshev was convicted of two murders involving dismemberment and cannibalism, with investigators suspecting him of as many as six additional similar crimes for which he was never formally charged. The full extent of his actions remained unresolved, leaving a pattern of suspected violence that the judicial record only partially captured.

Browne's case is defined less by his confirmed convictions than by the letters he later wrote to investigators, claiming a trail of killings spanning decades and multiple states. The gap between what could be proven and what he asserted — nearly fifty victims — placed him in an unusual category: a man whose full history may never be known. Investigators found enough corroborating detail to treat him as a credible suspect in several additional deaths, leaving his true scope a matter of ongoing uncertainty.

His victims were almost exclusively young children, and his crimes began when he himself was still a child — a detail that made his case both medically puzzling and socially alarming to Argentine authorities in the early twentieth century. The attacks spanned years and combined homicide with arson, suggesting a pattern of compulsion rather than opportunism. Even after institutionalization, he continued to harm those around him, ultimately rendering himself too dangerous for psychiatric care.

A deserter and petty thief who escalated into a spree of targeted killings, Lecián is notable for the specific pattern of his violence — directing lethal force repeatedly at law enforcement officers who moved to intercept him, ultimately killing four and wounding seven more in the span of a few months. His brief notoriety in early 1927 Moravia carried a folk-outlaw dimension, with popular songs casting him as a Robin Hood figure, though the killings of a prison guard during a failed escape attempt foreclosed any chance of clemency. Executed at twenty-six, he left an unusual legacy in the form of self-described imitators who explicitly invoked his name in subsequent years.

Operating across multiple households and marriages in Victorian England, she is believed to have used arsenic poisoning to systematically eliminate husbands and children, collecting life insurance payouts each time. What made her particularly difficult to detect was the mundane cover of domestic life — deaths in working-class families were common, and insurance fraud at this scale was rarely suspected of a woman. Her exposure came not through any single dramatic failure but through an offhand remark to a parish official about a child she had apparently already decided would not survive.