"The polygraph and polygraph methodology came relatively late to Bulgaria. It has a history of about 40 years, since the first polygraph instrument – a sixchannel Stoelting – arrived in 1968. This instrument was for the needs of Bulgarian intelligence to develop a system for training in deceiving the polygraph. It was necessary for intelligence operations for the infiltration of agents in the NATO bloc and the former Yugoslavia (at this time considered, although not an enemy, not a friend either). Later, in 1972, another Stoelting Ultrascribe was received. After the creation of a laboratory (and later institute) of psychology at the Ministry of the Interior, all polygraph experiments were conducted there. Initially, different information was collected by written sources (books, articles, documents) and by stories of people who were tested by polygraph behind the Iron Curtain"(...)