Jeong Cheol
The supposed treason of Jeong created a chance for the Westerners to regain their power. Seonjo made the Westerner Jeong Cheol oversee the investigation of the treason. The Yeongeuijeong (the premier) of the time, No Susin, and the Ueuijeong, Jeong Eonsin, were exiled due to their connections with Jeong Yeorip. (Jeong did not destroy the letters sent to him when he performed suicide or was murdered, and the letters proved to be useful when searching out those who had been close to Jeong.)