Henri Landru targets lonely, vulnerable women left behind by the war and seduces them with promises of marriage; he then lures them to houses outside Paris, where they vanish.

An investigation into Herbert Rowse Armstrong, known to history as "The Hay Poisoner," received a conviction in 1922 of murdering his wife with arsenic.

Putting on the front of a kindly baby farmer, someone who takes in the children of unwed mothers for a fee, Amelia Dyer became the most prolific killer in British history.