The Watchmaker of Montreuil operated across decades in late nineteenth-century Paris, leaving behind a pattern of suspicious deaths, sudden disappearances, and vanishing women whose fates were never fully accounted for in court. His case drew enough structural resemblance to that of Henri Landru — the serial targeting of women, the financial motives, the careful concealment — that prosecutors invoked his name during Landru's own trial as a point of comparison. What distinguished Pel was the persistent insufficiency of evidence: investigations were opened and closed, bodies were absent or unidentified, and the legal record remained incomplete even as suspicion accumulated. He was tried but never conclusively convicted of murder, leaving his full toll a matter of historical inference rather than established fact.

Fowler operated across two countries over more than two decades, evading serious consequences until a 1995 attack in Oregon led to his first conviction — by which point investigators suspected him of far more. The gap between his lone confirmed sentence and the breadth of activity attributed to him is what places him squarely in the record here.

Of the roughly 45,000 Union prisoners held at Camp Sumter during its fourteen months of operation, nearly 13,000 died from disease, malnutrition, exposure, and violence — a mortality rate that made Andersonville the deadliest site of the Civil War by some measures. Wirz oversaw the camp's daily administration during that period, and the conditions that developed under his command became the basis for the first war crimes trial in American history. He remains the only Civil War officer executed for war crimes.