South Korean police on Monday confirmed that two people who drove the 67-year-old man charged with stabbing the main opposition Democratic Party of Korea's leader Lee Jae-myung were unrelated to the attack.

The suspect, surnamed Kim, arrived at the Busan island of Gadeokdo on Jan. 1, a day before he attacked the liberal politician. The police investigation discovered that in addition to public transportation, he rode in cars of two individuals while going to the island off the country's southern port city.

"Kim got a ride from two people while traveling for the crime, but there is no possibility that the two were his accomplices," the special investigative unit of Busan Metropolitan Police Agency said in a media briefing Monday.

Kim has maintained that he worked alone, but officials said they are investigating to confirm anyone else was behind the attack. They also found that Kim had purchased the weapon used in the attack online around April of last year, which he modified and carried with him from when he left his home in Asan, South Chungcheong Province, Jan. 1.

Busan police said they will decide whether or not to reveal the suspect's personal information, including his photo and full name, after a deliberation committee on Tuesday. South Korean law states that the personal information of a suspect can be revealed only if a deliberation committee determines the cruelty, the extent of damage inflicted and the evidence indicating the crime is substantial.

Police also provisionally decided not to reveal which political party Kim is associated with. The decision sparked backlash from the Democratic Party, which said in a briefing Sunday that Kim's political party is "an important piece of evidence that is crucial to the motive of the crime."

Kim has remained mum on his specific motivation for attacking the liberal leader, saying it has been stated in testimony he gave to police. He did admit that he attacked with the intent to kill.

Kim has been arrested for attempted murder.

Lee, one of the most prominent figures on the opposition bloc, was stabbed in the neck by Kim during his visit to the site of a new airport on the island of Gadeokdo on Jan. 2.