Police in Brazil have arrested a man named Sailson Jose das Gracas, who has confessed to the killing of 42 people over the last decade in the city of Rio de Janeiro.
Police say they arrested him on Wednesday, shortly after he stabbed a woman to death in a city suburb.
He then confessed to killing another 37 women, three men and a two-year-old girl.
The police are searching for alleged victims and say they have found four.
In a police interview broadcast on Brazil’s TV Globo, the man said he would go out hunting, and he killed for the adrenaline.
He told police that if he was ever released from prison he would kill again.
He said he preferred victims who were white females, whom he strangled.
His three male victims had been killed when he was operating for hire, he added.
Das Gracas said: “I would wait for an opportunity to break into the house and kill,” adding that he would watch his victims for months before making his move.
Experts said Das Gracas appeared to be a psychopath who enjoyed the media spotlight and warned that what he said needed to be carefully checked.
Police said they had begun cross-referencing his confession with police reports and had already found four of his victims.