The allegation that the National Intelligence Service manipulated the press during the 2009 investigation of former President Roh Moo-hyun on suspicion of receiving bribes is yet another reminder of the NIS’ predilection for meddling in politics.

Earlier this week, Lee In-kyu, a former director of the central investigation division at the Supreme Prosecutors’ Office, who led the 2009 investigation, told a local newspaper that the NIS leaked information about the ongoing investigation and manipulated the press to humiliate Roh.

According to Lee, the prosecutors summoned Roh on April 30 and questioned him about a pair of high-end Swiss watches his longtime political sponsor had given to him as 60th birthday gifts. Roh replied that his wife threw them away when the watches became an issue.

Lee alleged that the news reports of Roh testifying that his wife threw the watches into a rice paddy, which first emerged on May 13, were a result of the NIS’ media manipulation. Indeed, immediately following the news coverage, the Supreme Prosecutors’ Office said they had not obtained testimony about throwing away watches into a rice paddy and vowed to find the person who had leaked the testimony. Roh jumped to his death 10 days later.

Another former member of the central investigation division at the Supreme Prosecutors’ Office has corroborated Lee’s claim, saying that the NIS suggested to the prosecutors that the watch story be “emphasized” to the press before summoning Roh, but that the prosecutors rejected this. However, the media focused on the watch story before Roh appeared for questioning. The former member of the Supreme Prosecutors’ Office also said that the prosecutors never mentioned Roh’s wife throwing watches into a rice paddy to the press.

It had long been suspected that the NIS leaked information about the Roh investigation for political purposes. The continuing protests against U.S. beef imports were a huge headache for President Lee Myung-bak at the time and there was a need to divert the people’s attention.

The National Intelligence Service said that it would launch an immediate investigation into Lee’s allegations and the main opposition New Politics Alliance for Democracy has called for a parliamentary investigation. The latest revelation is another blow to the NIS, whose former chief Won Sei-hoon ― in charge of the NIS at the time of the 2009 investigation ― now sits in prison for meddling in the 2012 presidential election. The NIS should stay true to its promise of complete reform and conduct a thorough probe ― this is an opportunity to prove to the skeptics that it intends to keep its pledge to stay out of politics.

While Lee accused the NIS of having manipulated the media, it should also be remembered that the Supreme Prosecutors’ Office also held regular press briefings on the Roh investigation even when the probe was underway.

The prosecutors should also come clean on the matter. Prosecutors are not free from charges that they also exploited the Roh investigation for political purposes. Lee’s disclosures do not exculpate him or the prosecutors from charges that they, too, leaked information to the press for political reasons.