Perhaps the most prolific serial killer of all time. Pedro Lopez of Colombia, raped and killed over 300 young girls across South America. Nicknamed the "Monster of the Andes," he was arrested in the 1980s and led police to numerous graves across Ecuador, Peru and Colombia.
He recited the story of his life. He was born to a prostitute, one of 13 children. He got caught fondling his younger sister in the late 1950s. In his adolescence, he was taken in by an American family into a school for orphans and reported he was molested by a man and ran away. By his teens, he stole cars. He claimed he was brutally gang raped in prison and later hunted down and killed each one of them.
He said when he left prison, he started stalking young girls and had killed over 100 by the late 70s. Racing from trouble in some parts, he kept moving around and said he killed on average 3 girls a week. He reported it was easy because the girls were sweet and trusting in Ecuador and the police assumed missing girls were sold into prostitution.
He was caught at one point and the police didn't believe him until a flood uncovered a mass grave of his victims. They sent him on to Ecuador to meet his fate.
We may think that our justice system is atrocious when a celebrity can kill his ex and get away it, but here's an awful twist -
Wikipedia: An A and E Biography documentary reports that he was released by Ecuadorian prison on 31 August 1994, re-arrested an hour later as an illegal immigrant, and handed over to Colombian authorities who charged him with a twenty-year-old murder. He was found to be insane and held in a psychiatric wing of a Bogotá hospital. In 1998, he was declared sane and released on $50 bail. The same documentary says that Interpol released an advisory for his re-arrest by Colombian authorities over a fresh murder in 2002.
In an interview with the National Examiner in 1999, he said this of his crimes -
"I went after my victims by walking among the markets searching for a girl with a certain look on her face — a look of innocence and beauty. She would be a good girl, working with her mother. I followed them sometimes for two or three days, waiting for when she was left alone. I would give her a trinket like a hand mirror, then take her to the edge of town where I would promise a trinket for her mother.
"I would take her to a secret hideaway where prepared graves waited. Sometimes there were bodies of earlier victims there. I cuddled them and then raped them at sunrise. At the first sign of light I would get excited. I forced the girl into sex and put my hands around her throat. When the sun rose I would strangle her.
"It was only good if I could see her eyes, it would have been wasted in the dark — I had to watch them by daylight. There is a divine moment when I have my hands around a young girl's throat. I look into her eyes and see a certain light, a spark, suddenly go out. The moment of death is enthralling and exciting. Only those who actually kill know what I mean.
"When I am released I will feel that moment again.
"It took the girls five to 15 minutes to die. I was very considerate. I would spend a long time with them making sure they were dead. I would mirror to check whether they were still breathing. Sometimes I had to kill them all over again," he admitted.
"They never screamed because they didn't expect anything would happen. They were innocent."
"My little friends liked to have company," he said. "I often put three or four into one hole. But after a while I got bored because they couldn't move, so I looked for more girls."