death squad 
noun
An armed paramilitary group formed to kill political opponents: the police operated death squads to eliminate prominent government opponents...
- Prosecutors accuse him of authorizing a military death squad to kill 15 suspected leftist guerrillas in 1991.
- In 2001, he was indicted for the killings carried out by a death squad that executed 75 political prisoners in the weeks after the coup.
- An Irish human rights worker hiding from a paramilitary death squad in Colombia has been allowed to leave an isolated region controlled by right-wing extremists.