The rivalry, mudslinging and negative campaigning between the two leading presidential candidates in South Korea are so bad that the loser faces a prospect of going to jail.

FILE - In this June 5, 2014, file photo, Park Won-soon, then candidate for Seoul city mayor of the main opposition party New Politics Alliance for Democracy celebrates his victory in the Seoul mayoral election at his office in Seoul, South Korea. Police say on Thursday, July 9, 2020, Park, the current mayor of South Korean capital Seoul, has been reported missing and search operations are underway. The Seoul Metropolitan Government earlier said Park did not come to work on Thursday and had canceled his schedule for the day. He was last seen on security video entering a park at the mouth of the hills late Thursday morning. He was elected Seoul mayor in 2011, upsetting his conservative opponent as an independent candidate backed by opposition liberals.