10 of the World's Most Prolific Serial Killers

Luis Garavito
Colombian police inspect corpses found in a mass grave at a farm in Guarne municipality in a case involving another serial killer, in 2016. Luis Garavito reportedly killed 300 people "for pleasure" in the 1990s. RAUL ARBOLEDA/AFP/Getty Images)

Colombian serial killer Garavito, dubbed "The Beast," reportedly liked to dress up in disguise — sometimes as a beggar or a disabled person, other times as a monk or an official from a charitable foundation — so that he could stalk impoverished children. After he talked his victims into going for a walk with him, he sexually abused them and slit their throats [source: Guardian].

Police finally caught him, and in 2000 he was convicted and sentenced to prison for 40 years for rape and murder of 111 children between 1992 and 1999. But he reportedly admitted to other murders as well, and some believe he may have killed more than 300 people [source: O'Driscoll].

After his conviction, Garavito helped lead authorities to the sites where he had buried several of his victims, in exchange for a reduced sentence. But after a public outcry, a Colombian judge ruled in 2011 that the killer would not be released early [source: O'Driscoll].

El Tiempo, a Colombian newspaper, obtained the results of a prison psychological examination in which Garavito was asked why he had killed so many. His reply: "I felt pleasure, even though when I had killed, the guilt came over me" [source: Heyden].