Over the course of five months in late 2011 and early 2012, four people were shot dead across a tight cluster of municipalities in the Essonne department — victims who, on the surface, had little connecting them beyond geography. What linked the crimes was a single 7.65mm semi-automatic pistol and, investigators determined, a single shooter whose prior knowledge of each location proved significant. Palmier received the maximum sentence available under French law, including a security detention provision — rarely invoked and designed for cases where standard release conditions are deemed insufficient.

Griffiths targeted vulnerable women working in street prostitution in Bradford, killing three within the span of roughly a year. His case drew particular attention after he appeared before a magistrate and identified himself as "the Crossbow Cannibal" — a self-dramatizing gesture that contrasted starkly with the grim disposal of his victims' remains in the River Aire. He received a whole life order, meaning he will never be considered for release.

What distinguished Corll's crimes was not only their scale but the infrastructure he built around them — recruiting teenage accomplices to funnel victims into his orbit, maintaining multiple residences as sites of captivity, and systematically disposing of remains across several locations over three years. The Houston Mass Murders went entirely undetected during his lifetime, surfacing only after one of his own accomplices turned on him. When the case broke in 1973, the confirmed victim count surpassed anything previously documented in American serial murder history.

Ng operated alongside Leonard Lake in a calculated, prolonged campaign of abduction and captivity that lasted roughly two years before discovery. The crimes committed at the Calaveras County cabin were distinguished by their systematic nature — victims were held, recorded, and subjected to prolonged abuse before being killed. The wide range in the estimated victim count reflects how thoroughly evidence was destroyed, a deliberate effort that complicated prosecution for decades and ultimately made his case one of the most expensive criminal trials in California history.

Over a span of years, Sherman used arsenic to eliminate three husbands and eight children under her care, operating within the domestic sphere in a way that made her crimes difficult to detect and easy to repeat. Her case drew widespread attention in the press and became one of the more closely examined American poisoning cases of the nineteenth century, partly because the victims were so numerous and so vulnerable. The 1872 conviction for second-degree murder left questions about the full extent of her actions that lingered long after sentencing.