Investigators raided the offices and residences of President Lee Myung-bak’s son and eldest brother on Wednesday as part of a probe into suspicions over a now-scrapped project to build Lee’s retirement home.

The raid came one day after the independent counsel team banned 10 people involved from traveling overseas.

They included the president’s son Si-hyung, former presidential security service chief Kim In-jong, former presidential chief of staff Yim Tae-hee and former presidential secretary of general affairs Kim Baek-jun.

Lee’s brother Sang-eun left the nation a day before the exit ban was issued.

They are accused of violating the real estate law when the son and the presidential security office jointly purchased a plot of land for the president’s retirement home.

Opposition parties and civic groups claim President Lee made the purchase under his son‘s name at a price far below the market value and the office paid higher-than-normal prices.

They also demand that the president unveil the source of the 600 million won ($543,000), which his son allegedly borrowed from his uncle Sang-eun for the purchase.

The prosecutors raided Sang-eun’s houses in Seoul and his auto parts company DAS in Gyeongju, North Gyeongsang Province, as well as Si-hyung’s house and office in Gyeongju and two real estate agencies involved in the deal.

Assistant counsel Lee Chang-hoon on the investigative team said the prosecutors are trying to secure records of money transactions, contracts and other related evidence. The search warrants were issued Tuesday.

The investigative team is also tracing banking transactions of other people including Lee Si-hyung.

The prosecutors sent summons to three officials at the presidential security service including Kim Tae-hwan, who is known to have been in charge of purchasing the land.

DAS officials said Lee Sang-eun went on a business trip to China to visit partner companies and is scheduled to return to Seoul on Oct. 24.

They denied that President Lee’s eldest brother is trying to avoid the investigation.

The prosecution is said to be trying to contact the seller of the land identified by surname Yoo. He is reported to have been in the U.S. since May.

The prosecutors’ special probe will last 45 days at most and will conclude before late November.

By Kim Young-won (wone0102@heraldcorp.com)