Guilty of treason

When two left-leaning political parties merged to form The Unified Progressive Party (UPP) in December 2011, and were later joined by elements of a third party, South Korea's socialists believed they had discovered a new voice.

This sentiment was stoked by the UPP winning eight new seats in the general election held in April the following year, bringing its total to 13 out of the 300 in the National Assembly.

Officially describing itself as a progressive political grouping, the party advocates an end to military cooperation with the United States, achieving peace with the regime in North Korea, the abolition of nuclear weapons on the Korean peninsula and, eventually, the reunification of the two neighboring states.

However, events soon took a turn for the worse when the party's Central Committee launched an investigation over allegations of irregularities in the selection of its proportional representation candidates for parliament. Although the UPP's four joint leaders resigned to take responsibility for the scandal, things were about to get much worse for the fledgling party.

Plotting rebellion

On September 5, 2013, the National Intelligence Service (NIS) swooped down on one of the party's representatives, Lee Seok-ki, accusing him of plotting to carry out a rebellion with 130 followers.

The NIS said it had evidence that Lee headed the cell known as the Revolutionary Organization. They also claim he had discussed the best ways in which to sabotage key installations and infrastructure across South Korea in the event of war breaking out with the North.

The homes and offices of UPP officials were searched for further evidence and parliament was required to lift Lee's immunity from prosecution as a politician - the first time a sitting South Korean lawmaker has been arrested on rebellion charges.

It also emerged that Lee had been previously arrested on suspicion of subversion in 2002, although he was later given a presidential pardon.

'Medieval witch hunt'

Before the vote in parliament to lift his immunity, Lee referred to the charges as a "medieval witch hunt." Lee said: "The National Intelligence Service has accused me of a horrible allegation - conspiracy to cause a rebellion - and has conducted a medieval witch hunt by mobilizing the conservative press," he said.

Lee and the UPP insisted the accusations were fabricated by South Korea's internal security force in order to distract attention away from allegations that the NIS was involved in attempting to influence the 2012 presidential election.

Guilty verdict

But the politician's claims weren't enough to change the outcome of his trial. On February 17, a South Korean court sentenced the left-wing lawmaker to 12 years in prison. Prosecutors said he had gathered information on US bases, communications and a power plant and plotted an armed rebellion in support of North Korea in the event of a war on the Korean Peninsula.

The Suwon District Court said in its ruling that Lee's punishment was inevitable because his plot posed a "substantial and apparent threat" to South Korea.

According to media reports, it was the first time since democratic elections took place in 1988 that the South's National Security Act has been used against a member of parliament. Lee's lawyers said they would file an appeal against the conviction and lambasted the judiciary for what they said was its failure to protect democracy.

North Korea had stepped into the debate, with the Committee for the Peaceful Unification of the Fatherland denying Pyongyang had been involved in the plot.

"The NIS and conservative forces are concocting a scheme to falsely accuse UPP members of treason" and to link it to the North Korean regime, the organization said.

"It is a fabrication deliberately planned by those who do not want inter-Korean relations to improve and tensions to ease," it added.

However, those claims cut little ice with the public. According to a Gallup poll conducted in September, 61 percent of South Koreans said they believed the charges laid against Lee were true. Addressing the Suwon District Court, prosecutors recently said Lee's plans had posed a grave threat to the nation's security and they demanded a 20-year sentence.

Threat to national security

"Heavy punishment is necessary as [Lee] ordered [Revolutionary Organization] members to prepare for riots and warfare, abusing his status," the prosecutors said.

Lee had also been accused of contravening South Korea's stringent National Security Law by singing songs in praise of North Korean founder Kim Il-sung.

"There was a good degree of shock and outrage about what Lee was allegedly planning to do, particularly among conservatives and military veterans," said Daniel Pinkston, a North Korea analyst with The International Crisis Group in Seoul.

"But this is a fringe group on the very far left with little in the way of political representation, so I would say that the majority of the South Korean public were not all that alarmed," he said. "The party was not popular and did not have the ability to muster a significant portion of society."

Advocates of the North

But other analysts shake their heads at the very idea of people living in South Korea's free and open society advocating reunion under the banner of Kim Jong Un's government.

"I find it utterly ridiculous that they hanker after a North Korean lifestyle," Yoichi Shimada, a professor of International Relations at Fukui Prefectural University, told DW

"It just goes to show that these people exist in every society, even one in which they see the misery that is forced on people just over the border," he added. "It's terrible that they choose to turn a blind eye to things that are going on [in North Korea]."