(also, especially in American usage: ‘stoolie‘ & also written ‘stool–pigeon’); plural: ‘stool pigeons‘; for the right pronunciation of this word, please click here)
a person who acts as a decoy, i.e. an innocent person who is used to mislead the police or others, especially the media, so that the real culprit or criminal can hide or escape;
(also called ‘nark’ & ‘stoolie’ in this context) a person, usually a criminal him/herself, who acts as an informer to the police, giving away the secrets of the other criminals to the police,
When the entire scheme was leaked, the organisation used our manager as the stool pigeon so that the media and the police focus their attention on him and meanwhile, the top brass can clear their involvement in the affair.
Most of the big criminal bosses were brought to the justice with the help of the low-level criminals in the gangs who, out of fear of getting arrested or out of greed for money, turn stool pigeons and give away the secrets of the gang activities.
Some of the bloggers and website owners on the internet are becoming unwary stool-pigeons or stoolies for the investigating agencies like the CIA world over, and more and more personal information of their contacts/friends is being involuntarily passed on to them.