The Busan Metropolitan Police Agency said Wednesday that the political ideology of the suspect in the stabbing of the main opposition leader led to the knife attack.

“The attacker had vented resentment toward the Democratic Party leader and wanted to stop Lee from becoming president and prevent him from securing a majority of seats in the upcoming general election by giving nominations to specific persons,” said Woo Cheol-moon, head of the Busan Police Agency, as he briefed the press on results of the attack’s investigation.

Woo added that the suspect had also committed the crime because he thought the opposition leader had not been “properly punished” after the trial over his corruption charges was postponed.

The investigation results were reached by thoroughly analyzing the suspect’s call log, using digital forensics and looking at his behavioral analysis, according to officials. They added that there was no mastermind or accomplice.

However, the identity of the 67-year-old attacker -- only known so far by his family name Kim -- including his name, a portrait photo and political party affiliation will not be disclosed, as the case did not meet legal conditions for such a revelation, according to police.

The suspect in Lee’s knife attack apologized on Wednesday for the inconvenience caused as he was being referred to the prosecution.

“I am sorry. ... I am sorry for causing concern to the public,” he told a group of reporters when asked if he had anything to say to Lee while he was being transported to the prosecution from Busan Yeonje Police Station.

Meanwhile, Democratic Party of Korea leader Lee Jae-Myung said on the same day that his stabbing attack would serve as a watershed in ending “warlike politics” of killing and eliminating opponents in South Korea.

The remark came as the chairman left Seoul National University Hospital eight days after the incident, where he had received surgery for vascular reconstruction and the removal of blood clots in his neck.

“I sincerely hope that the incident, which surprised all of us, would be a catalyst in bringing an end to the politics of hatred and confrontation, and restore proper politics where (we) respect each other and compromise,” Lee said as he was discharged from the hospital.

“At one point, our politics have turned into the politics of death that gives birth to despair,” Lee said. “Now, taking this incident as an opportunity, I hope that all of us, including myself, can chew over (the attack) and make efforts to rebuild politics that can create hope,” he added.

Lee will return home and continue treatment there for the time being.

The opposition leader was stabbed in the neck on Jan. 2 after touring the construction site of a new airport on Busan’s small island of Gadeokdo.

The attacker had pretended to be a supporter and approached Lee by asking for an autograph before stabbing him in the left side of the neck with a knife he purchased in April last year, the police investigation found.