Monster of Rio de Janeiro, Brazil.

A man named Sailson  Jose das Gracas might be Said to be Brazilian most prolific serial killers of all time. He was said to have killed 39 women in the Rio de Janeiro over the past nine years.

                     
Pix/cnn

According to cnn, he said that he carried out the first slaying when he was 17 and continued to kill over the next decade.
I started robbing purses and as I got older, I started having a different thoughts. My thoughts started changing. From stealing, I started thinking about killing.
Sailson, reported to be 26-years-old, said he didn't kill impulsively but stalked his victims.
Rio police said they arrested Sailson on Wednesday on suspicion of killing a woman in the suburb of Nova Iguacu. He confessed to that homicide and then told police about the other killings.

The self-declared killer said he had "no regrets" about his actions and would kill again if set free.
"What is done is done," he said, If I leave here in 10, 15, 20 years, I'll go back to doing the same thing.