The suspect in the stabbing of main opposition Democratic Party(DP) leader Lee Jae-myung testified that he had carried out the attack in a bid to prevent the party chief from becoming president.

In a briefing on the final investigation results, the Busan Metropolitan Police said Wednesday that the man in his 60s, surnamed Kim, appears to have committed the crime because he felt that the DP leader was not being properly punished as his corruption trials were being delayed.

The police believe that Kim had no accomplice based on an examination of seized items, a digital forensics survey, as well as a call history and trace analysis.

The police earlier apprehended a man in his 70s suspected of being Kim's accomplice, but released him shortly after it was found that he had promised to send the suspect's so-called "excuse note" to the media and the suspect's family once the crime was committed.

The Busan Metropolitan Police had established an investigative headquarters consisting of 68 personnel to conduct a probe into the case for nine days.