President Lee Myung-bak’s only son was questioned Thursday over alleged irregularities in connection with his father’s now-defunct retirement home project.

Lee Si-hyung, 34, became the first child of an incumbent president to be summoned as a criminal suspect.

“I will speak the truth, answer sincerely,” he told reporters at the independent counsel’s office in southern Seoul in the morning. He was accompanied by lawyers and presidential security guards. 

On behalf of the president, Lee bought a plot of land in southern Seoul together with the presidential security service.

Prosecutors will look into whether he broke the law on the use of a real name in property transactions and if the security service’s fund was misappropriated for his share of the purchase.

Cheong Wa Dae declined to comment, saying it is no longer a matter for the presidential office to get involved in.

President Lee had no public schedule on the day, nor the day before his son was summoned. His aides said the president was preparing for international conferences he is scheduled to attend next month.

According to reports, however, some officials are concerned about how far the investigation will go as the special counsel could summon not only Lee’s eldest brother but also first lady Kim Yoon-ok for questioning.

The junior Lee, who in 2008 reported his assets to be only 36 million won ($33,000), paid 1.12 billion won for the land. The Presidential Office later explained that the son had borrowed 600 million won from a bank, using his mother’s share of the residence in Nonhyeon-dong as collateral, and the rest from his uncle, Sang-eun.

The special investigative team also plans to summon Sang-eun, the President’s eldest brother, as soon as possible as he returned from an overseas trip on Wednesday. The 79-year-old chairman of automotive seat maker DAS had left for China on a business trip on Oct. 16, a day before the special investigative team sought a travel ban for him.

The opposition Democratic United Party urged Lee Si-hyung to give a clear answer as to why the land for the president’s retirement home was bought under his name.

“The scandal centers on whether President Lee himself directed (the whole process of the project). Lee (Si-hyung) has to explain whether he was only following his father’s orders as reported by the media,” said Jin Sung-joon, spokesman for DUP presidential candidate Moon Jae-in.

In May 2011, Si-hyung bought a plot of land in Naegok-dong on the southern edge of Seoul jointly with the presidential security service. The project included building auxiliary security facilities inside of the president’s residential complex.

The opposition party and civic groups have claimed that Si-hyung and the security office did not evenly divide the cost of the land and this allowed the president’s son to pay less than what his share was actually worth. The security had paid an extra amount of between 600 million won and 800 million won, they claimed.

By Cho Chung-un (christory@heraldcorp.com)