A 16-year-old boy has acknowledged murdering 12 people in southern Brazil, according to a police investigator who described his chillingly calm confession. The teenager, whose identity was not revealed because he is a minor, allegedly told police he killed in fits of rage or out of revenge - or, in one case, because the victim wanted to date his sister, police inspector Enizaldo Jose Plentz said Friday. Police have enough evidence to prove that the unemployed high school dropout killed at least six people with an initial shot to the head before riddling their bodies with bullets, Plentz said. Authorities were still working to determine if he killed the other six. "The news stunned everyone," said Salete Lanius, a receptionist at a hotel in the teen's home city of Novo Hamburgo, a shoe manufacturing town where the killings took place. "For me, he is just an evil person, and the fact that people like him live among us is really scary."