section_path: Prosecutorial career/Early career
section_name: Early career
paragraph_text: Early career
  
  Yoon started his career at Daegu Public Prosecutor's Office in 1994. He headed the Special Branch and Central Investigation Department, both of which investigate corruption-related cases. In 1999, he arrested Assistant Commissioner Park Hui-won, who was corrupt despite strong objections from bureaucrats in the Kim Dae-jung cabinet.
  
  In January 2002, Yoon worked briefly as a lawyer at Bae, Kim & Lee but left because he felt the position was unsuitable. Upon his return as a prosecutor, he prosecuted pro- Roh Moo-hyun figures such as Ahn Hee-jung and Kang Keum-won. In 2006, he apprehended Chung Mong-koo for his complicity in a slush fund case at Hyundai Motor Company. In 2008, he worked for the independent counsel team resolving the BBK incident related to President Lee Myung-bak.
  
  In 2013, Yoon led a special investigation team that looked into the National Intelligence Service (NIS)'s involvement in the 2012 NIS public opinion manipulation scandal. Yoon sought the prosecution of the former head of the NIS, Won Sei-hoon, for violating the Public Official Election Act. He also accused Justice Minister Hwang Kyo-ahn of influencing his investigation. As a result, he was demoted from the Seoul prosecutors' office to the Daegu and Daejeon High Prosecutors' Office.
  
  Yoon later became head of investigations in the special prosecutor team of Park Young-soo, which investigated allegations of the 2016 Choi Soon-sil scandal involving Choi, Samsung vice-chairman Lee Jae-yong, and then-president Park Geun-hye, which led to the impeachment of the president in December 2016.
  
  On 19 May 2017, the newly elected president Moon Jae-in appointed Yoon as chief of the Seoul Central District Prosecutors' Office. The prosecution went on to indict two former presidents Lee Myung-bak and Park Geun-hye, three former NIS chiefs, former chief justice Yang Sung-tae, and more than 100 other former officials and business executives under his tenure. Yoon also led an investigation into accounting fraud at Samsung.