One of the world’s most prolific serial killers might still be out there. Pedro Lopez is linked to more than 300 murders in his native Colombia and in Ecuador and Peru. At least one-third of those murders were tribal women. After Lopez’s arrest in 1980, police found the graves of more than 50 of his preteen victims. He was later convicted of murdering 110 girls in Ecuador and confessed to 240 more murders in Colombia and Peru. The “Monster of the Andes” didn’t even spend 20 years in prison, as he was released in 1998 for good behavior. More than 20 years since, his whereabouts remain unknown.