Guimarães worked as a nurse in the Salgado Filho Hospital in the Méier district of Rio de Janeiro, Brazil.
He was caught in 1999 when a hospital porter saw Guimarães fill a syringe with potassium chloride and inject a comatose patient who immediately died.
[2] He told a television reporter prior to his trial, "I don't regret what I did", adding "I did it to those in irreversible comas and whose families were suffering.
"[4] One possible motive for the murders is thought to be the fact that he was paid $60 a time to inform local funeral homes of a patient's death so that they could contact the deceased's relatives.
[4] According to Josias Quintal, Rio's secretary for public security, "He may have begun doing it to earn money and then just lost control".