unofficial collaborator

An unofficial collaborator or IM (German: [iˈʔɛm] ; both from German: inoffizieller Mitarbeiter), or euphemistically informal collaborator (informeller Mitarbeiter), was an informant in the East Germany who delivered private information to the Ministry for State Security. At the end of the East German government, there was a network of around 189,000 informants, working at every level of society.