The independent counsel investigating the purchase of land by President Lee Myung-bak for his retirement home suspects that officials of the Presidential Security Service falsified and destroyed evidence and attempted to cover up their lawbreaking. If true, their action would constitute a serious criminal offense and have grave political consequences.

On Friday, the independent counsel’s investigators questioned three officials from the security service, whom they had summoned as criminal suspects. They said they had summoned them because discrepancies were found between the statements those involved in the case had made and the materials they had obtained from the presidential office. The officials were reportedly involved in handling the case when the allegedly illegal land purchase came to light last year.

In 2011, the security service, which had wanted to build an office for its detail inside the planned residential compound, bought plots of land in the outskirts of Seoul together with President Lee’s son, Si-hyung, who apparently acted as the president’s proxy in the deal. The security service was suspected of over-reporting the value of the land for the office and underreporting that of the land for the retirement home, making it possible for the president to receive illegal gains.

The independent counsel, which previously questioned the president’s son about the land purchase, was told that he had borrowed 600 million won ($550,000) from the president’s older brother and the rest from a bank. The independent counsel, who obtained the IOU the president’s son reportedly presented to his uncle, is now demanding the presidential office submit its computer file for confirmation.

The presidential office will have to submit the file immediately. Should it refuse to submit the file, the independent counsel would have no other option than to seek a search and seizure warrant from the court.

The land-purchase case is not a complicated one. What the independent counsel will have to do is determine whether or not the president, or his son, attempted to make illegal gains at the expense of taxpayers with the help of the security service officials. The independent counsel will also decide whether or not he breached the law banning proxy property transactions.

The presidential office will have to acknowledge that the independent counsel is authorized to make any demand if it is deemed legitimate and necessary to the investigation. A refusal to comply with such a demand would amount to a self-inflicted wound.