ANALYSIS: Confidential informers play a significant role in police investigations around the world, but there are also recognised risks of informers committing ‘treachery’ – either intentionally feeding officers false information, or revealing their identity to a third person; new research by Sgt David Younan and Crime Analyst Sarah Harmer – both of London Police Service, Ontario – examines the instances of treachery by Service informants over a two-decade period, and suggests evidence-based approaches that policing can implement to minimize the risks.