Stationed in wartime Melbourne, Leonski killed three women in the span of a few weeks during a period when the city was already shadowed by the threat of Japanese air raids. The case became entangled in questions of military jurisdiction, ultimately resulting in a court-martial rather than a civilian trial — an outcome with no precedent in Australian legal history. His execution in 1942 closed an episode that had unsettled both the host population and the Allied command at a particularly fragile moment in the Pacific war.

His victims were primarily First Nations women in Vancouver's Downtown Eastside — a population whose deaths drew little official scrutiny, which appears to have been central to how Jordan operated across more than two decades. He used alcohol as a weapon, coercing women into drinking lethal quantities and relying on the likelihood that their deaths would be attributed to poisoning rather than homicide. Despite being linked to eight to ten deaths, he was convicted of manslaughter in only one, serving six years before his release.

Operating over more than a decade, Ney exploited positions of access — as a caregiver and through residential burglaries — to reach his victims, a pattern that allowed him to evade identification for years. The use of a mask and concealing clothing across the majority of his offenses was methodical enough to sustain a distinct public alias before his eventual arrest and confession. The German court's finding of particular severity of guilt reflects the sustained, varied, and institutional nature of the harm involved.

His path to China's presidency was secured not through military victory or popular mandate but through the systematic bribery of members of parliament — an episode that became one of the more brazen examples of institutional corruption during the fractious warlord era. As the dominant figure of the Zhili clique, he wielded both military and political power at a moment when central authority in China had largely dissolved into competing regional factions.

A French privateer whose career encompassed both celebrated naval aggression and the trafficking of enslaved people, Surcouf operated across two distinct but equally consequential registers of harm. His capture of more than forty prizes during the Revolutionary and Napoleonic Wars made him a significant disruptor of British commercial shipping in the Indian Ocean, yet his parallel engagement in the illegal slave trade — conducted before he held any legal authority for it — points to the opportunism that defined his broader career. The fortune he ultimately accumulated drew from both activities without clear distinction between them.

What distinguishes Marquette in the record of American serial crime is less the number of victims than the bureaucratic milestone his case produced — his pursuit prompted the FBI to expand its Ten Most Wanted List for the first time. His crimes spanned more than a decade across two periods of freedom, suggesting a pattern that incarceration interrupted but did not resolve.

A minor criminal whose escape from a wartime Finnish prison led to an act of violence wholly disproportionate to anything in his prior record, Koljonen killed six people — most of them members of a single rural family — using an axe, in a farmhouse whose able-bodied men had been taken away by conscription. The circumstances made his victims particularly vulnerable, and the crime stood out starkly enough that he became the last person in Finland to be executed for a civilian offense.

Sodeman operated in Victoria during the 1930s, targeting young girls in attacks that caused widespread public fear around the safety of children. His crimes were notable both for the vulnerability of his victims and for the psychiatric examination that followed his arrest, which found evidence of a neurological condition that factored into legal proceedings at the time. He was hanged at Pentridge Prison in 1936 after confessing to four murders.

Over four years, Fuchs conducted a sustained bombing campaign against immigrants and those he perceived as sympathetic to them, demonstrating a methodical operational capacity that kept Austrian authorities from identifying him for years. His use of mail bombs allowed him to strike at a distance, and the five successive waves of attacks showed a deliberate escalation rather than impulsive violence. The scale of harm — four dead, fifteen wounded — was accompanied by the psychological weight of a campaign that kept potential targets in prolonged fear.