Won Sei-hoon, a former director of the National Intelligence Service, humiliated not just himself but the intelligence agency on Monday when he subjected himself to a prosecutors’ inquiry into an allegation that he interfered in domestic politics and attempted to influence the Dec. 19 presidential election. The prosecution said he could be summoned for additional questioning once or twice more before its investigation was completed.

The case also involved two NIS agents, who were accused of posting political comments in favor of the ruling Saenuri Party’s presidential nominee, Park Geun-hye, and at the expense of her adversary, Moon Jae-in of the opposition Democratic United Party, during the run-up to the election. The prosecution, which took over the case from the police, is now looking into an allegation that the agents attempted to manipulate public opinion on the presidential contenders on orders from the director.

The prosecution is also looking into another allegation that Won issued instructions to the NIS staff on several occasions between May 2009 and November 2012, calling for efforts to help the government win over young people and deal with criticism. Won also allegedly told his staff to help form a favorable public opinion on former President Lee Myung-bak’s pet projects, such as the four-river restoration project.

Documents allegedly containing Won’s instructions were made public by the main opposition party last month. An investigation by the prosecution looked inevitable, given the severity of the suspicions that he breached the laws banning officials of the agency from engaging in political activities and electioneering.

Tipped shortly thereafter on his plan to leave the country, the prosecution banned him from traveling overseas. At the time, suspicions were raised that he had wanted to stay abroad long enough to avoid being investigated. If this is true, planning such a trip was inappropriate for a former spy agency chief, who would have to be protected by a bodyguard from being kidnapped for a certain period of time after his retirement.

If Won is found to have succumbed to the lure of engaging in clandestine domestic political activities, he will not be the first to have done so. Some of his predecessors were punished for breach of the law.

It is important for the offenders, be it the top spymaster or a low-level officer, to be held accountable. No less important is to determine, through the prosecution’s investigation, what institutional changes are needed to prevent the agency from falling into recidivism.