A man who infiltrated some of Liverpool's most dangerous criminals has revealed what it takes to become a "rat".
David Taylor, not his real name, spent more than a year working covertly to target serious criminals involved in drug smuggling in Liverpool. In a rare interview with The Guardian, he reveals how he created a cover story to go undercover on an operation infiltrating a network of criminals in Liverpool.
Mr Taylor started undercover work in the 1990s catching dealers by posing as a buyer. But the work became more intense after moving to Liverpool in 2003, when he became an "employee" at a fake business run by covert police officers.
