Coming face to face with a probable psychopath was enough to make Dr Leanne ten Brinke rethink her career choices. Early in her 20s, while studying forensic psychology in Halifax, in the Canadian province of Nova Scotia, Ten Brinke was volunteering at a parole office, which would hold weekly group meetings for released sex offenders. “Most of the men showed contrition,” says Ten Brinke. “They really seemed to recognise the damage that they had done.” Except for one. The treatment programme seemed “like a game to him”, she says. One week, in a discussion about the impact their crimes had on victims, this rapist stared at Ten Brinke and, smiling slightly, started to say how much his victim looked like her, “and how I was ‘his type’. Clearly he was trying to scare me, and he did.”