Особая тройка НКВД — орган внесудебного вынесения приговоров, существовавший в СССР в 1935—1938 годах, обычно на уровне области. Состоял из начальника областного управления НКВД, секретаря обкома и прокурора.
http://en.wikipedia.org/wiki/NKVD_Order_no._00447NKVD Order № 00447 by July 30, 1937 (Russian: О репрессировании бывших кулаков, уголовников и других антисоветских элементов) ("About repression of former kulaks, criminals, and other anti-Soviet elements") was undersigned by Nikolai Yezhov and approved by Politburo during the Great Purge.
To execute this order, numerous NKVD troikas were created on republican and various regional levels (krai and oblast). Investigation was to be performed by operative groups "in a speedy and simplified way", the results were to be delivered to troikas for trials.