Merciless

A killer (Bruno Gagliasso) infiltrates the police and so begins a cat-and-mouse game with a forensic psychologist Vera in this Brazilian thriller

You learn early on in the opening episode of this Brazilian thriller who the killer is, but that doesn't spoil the suspense in the slightest. Charismatic young lawyer Edu is working on a senator's election campaign by day and raping and murdering women by night. He infiltrates the police and so begins a cat-and-mouse game with forensic psychologist Vera.