Former female wrestler Juana Barraza was found guilty in March 2008 of murdering at least eleven elderly women in Mexico city over a period of seven years. Barraza, who became known as the "little old lady killer", admitted to murdering three women, and told investigators that it was because of her lingering resentment for the abuse that she'd suffered as a child at the hands of her alcoholic mother. Mike Lanchin has been hearing from Mexican neuro-psychologist Dr Feggy Ostrosky, who spent days interviewing Barraza in jail, trying to understand what had turned her into a serial killer.

(Photo: Former female wrestler Juana Barraza. Credit: David Deolarte/AFP/Getty Images)