The prosecution concluded Monday that the leadership of the minor opposition People’s Party was not involved in a fake tipoff about President Moon Jae-in’s son, which surfaced during the presidential campaign in May.

Announcing the results of the 35-day probe into the case, the Seoul Southern District Prosecutors’ Office indicted former lawmaker Kim Seong-ho and lawyer Kim In-won, who were on the campaign team for a “fair election” for the People’s Party’s presidential candidate Ahn Cheol-soo.

The prosecution said there was no evidence that the party’s co-founders Ahn and Park Jie-won, or Rep. Lee Yong-ju who led the campaign team, had been a part of the fabrication scheme.

Four days ahead of the May 9 election, the centrist opposition party revealed that Moon, then the front-runner for the Democratic Party of Korea, peddled influence to get his son hired at a state-run agency in 2006. He was then a senior presidential secretary for civil affairs.

The party disclosed an audio file as evidence in which a person, who claims to be a schoolmate of Moon’s son, Joon-yong, from Parsons School of Design in New York, said Moon’s son had landed a job at the Korea Employment Information Service due to his father’s influence.

The recording had been fabricated by the People’s Party’s Lee You-mi and the schoolmate of the younger Moon in the audio file turned out to actually be her brother, according to the prosecution. The party’s former Supreme Council member Lee Joon-seo willfully neglected the possibility that the tip-off had been falsified, it said.

The prosecution filed charges against five people -- including Lee Joon-seo, Lee You-mi and her brother -- for conspiring to fabricate evidence to smear Moon on the campaign trail.

The prosecution charged them with violation of the election law for spreading false information, saying the party officials had disclosed the phony audio file without any efforts to verify its authenticity.

An internal probe by the People’s Party also concluded that the fabrication was Lee You-mi’s lone act. Lee, however, claimed the party’s leadership ordered her to do so.

The People’s Party later formally issued an apology for the fabrication, promising to start anew, following a party meeting Monday afternoon.

“We deeply apologize for causing trouble to the public with the tip-off fabrication case that took place during the presidential campaign,” it said in a statement, acknowledging its responsibility for failing to “filter illegal acts by a party member.”

Allegations surrounding Moon’s son had been one of the key points of attack against then-front-runner Moon during the presidential campaign period.

The scandal placed the People’s Party into a crisis 1 1/2 years after its launch. Its support rating stood at 4.9 percent, according to a survey by Realmeter on 2,448 people aged 19 or over from July 24-28.

By Ock Hyun-ju (laeticia.ock@heraldcorp.com)