Edited image: Forensic police in front of the main entrance of the Pôle Universitaire Léonard-de-Vinci where John Dowling (inset), a 66-year-old teacher from Ireland, was stabbed to death. Photograph: Philippe Lopez/AFP/Getty Images

A 66-year-old Irish lecturer was killed in front of students from the university where he had taught for 20 years in the Paris suburb of Courbevoie on(...)