Matthew Falder: Experts on 'pure monster'

A university lecturer who hunted for vulnerable victims online boasted he would "never be caught".

It took the UK's National Crime Agency four years to catch Dr Matthew Falder, who worked at the University of Birmingham.

British police formed a unique taskforce with the FBI, US Homeland Security, Europol and GCHQ to track Falder, who hid behind email encryption, pseudonyms and dark web paedophilia sites.