Despite being believed to be one of the most prolific serial killers of the twentieth century, he was released in the late 1990s.[6] Javed Iqbal Pakistan 1998 to 1999 100 100 Child-murderer and rapist, known as "Kukri", Iqbal murdered 100 street children by strangling them and covering up his crimes by dissolving the bodies with acid. He was arrested in 1999 thanks to a letter he sent a newspaper, and was set to be executed in the manner described by the judge who stated, "You will be strangled to death in front of the parents whose children you killed, Your body will then be cut into 100 pieces and put in acid, the same way you killed the children."[7] However, he died in custody before he could be executed.[8] Mikhail Popkov Russia 1992 to 2010 78 81 Serial rapist-killer nicknamed "The Werewolf", who was active for two decades in Angarsk, Irkutsk and Vladivostok. After being convicted of 22 murders in 2015, he confessed to an additional 59 murders, of which he was convicted of 56 in 2018.[9][10] Daniel Camargo Barbosa Colombia Ecuador Brazil (alleged)[11] 1974 to 1986 72 180[11] Child and woman murderer, believed to have possibly raped and killed over 150 victims, primarily targeting female children as they were more likely to be virgins.