Maníaco da Cantareira

Ademir Oliveira Rosário (born 1971), known as The Cantareira Maniac (Portuguese: Maníaco da Cantareira), is a Brazilian serial killer and serial rapist who gained notoriety for murdering two teenagers in 2007. The crimes were committed after his release on probation from a psychiatric clinic, where he had been interned for a 1991 manslaughter conviction and other charges. For the latter crimes, he was convicted and sentenced to 57 years imprisonment.

Early life Born in 1971 in São Paulo in a family with seven other siblings, Oliveira's childhood was described as reportedly normal, despite being born deaf and mute. However, according to one of his sisters, he started to exhibit unstable and bizarre behavior as a teenager, but did not cause any major disruptions to his family members.

Release and sexual assaults In the early 2000s, Oliveira was transferred to a psychiatric hospital in Franco da Rocha, where he was eventually given permission to leave on November 25, 2006. Like Oliveira, Messaggi was attracted to teenagers aged 14 to 15, whom he often lured to nearby forests with offers of sex in exchange for candy and soft drinks. In total, it is believed that he did this to approximately 21 victims from March to September, and reportedly acted alone.

Upon further inspection, it was determined that both had been stabbed and possibly sexually assaulted, as coroners located puncture wounds from a sharp object on both of their bodies. Now considered a homicide investigation, detectives quickly learned that only a day prior to the brothers' disappearance, another trio of boys had been attacked, but managed to escape. When interrogated, they described their assailant as a young black man with a scar on his face and a shaved head, who was possibly deaf-mute. They eventually tracked down a brother of Oliveira, who told them that he was currently incarcerated at a psychiatric hospital for a violent indecent assault. He also denied raping and killing Francisco, pinning it completely on Messaggi. Due to this, his attorney, Marcos Figueiredo Martins, pleaded with the judge to have his client acquitted on the grounds of insanity and thereafter transferred to a mental health institution, arguing that he could not possibly have been in a stable mind when he had committed the murders.

In a rebuttal to that assessment, prosecutor Eduardo Campana pointed out that the psychiatric reports indicated that Oliveira was sane at the time of the crimes and thus fully culpable for his actions. For his alleged role in the crimes, Messaggi had already been convicted for participating in Josenildo's death in 2009 and was sentenced to 31 years imprisonment, but has continued to appeal the sentence, professing his innocence.

Shortly after Oliveira's arrest, an investigation into the practises at the Franco da Rocha hospital established that there were numerous irregularities, including understaffing and lack of proper storage for the inmates' medicine.