The special counsel is expected to request a 15-day extension over the weekend to continue its probe into President Lee Myung-bak’s now-scrapped retirement home project in which critics say taxpayer money was used, officials said Wednesday.

Following first lady Kim Yoon-ok’s return from an overseas trip on Sunday, special counsel Lee Kwang-bum’s team will have only two days to question her or make a decision to bring charges against anyone, as the 30-day investigation period ends next Wednesday.

The probe can last longer if the 15-day extension is requested by the special team and approved by the president.

“We have already finished reviewing (whether to request the extension) and the matter will be finally decided over the weekend,” assistant special counsel Lee Chang-hoon said during a press briefing.

“If the extension is requested, it would be sometime on Friday or Saturday,” he said, adding that President Lee would not have any problem with the approval despite his overseas visit.

The counsel’s team already grilled President Lee’s eldest brother and son last week over allegations that the president’s only son, Lee Si-hyung, and the presidential security service used public funds and violated real estate laws when they jointly bought a plot of land last year for the retirement residence, which was to be built in Naegok-dong on the southern edge of Seoul.

The cost was allegedly not shared evenly, with the security service paying too high a price for the site for security facilities, at the expense of taxpayer’s money.

On Monday, the team announced its plan to question the 65-year-old first lady who is suspected of having played a role in the alleged irregularities by providing her stake in a private house in Nonhyun-dong in southern Seoul as collateral to help her son take out a 600 million won ($542,000) bank loan.

The younger Lee claimed he supplemented that amount with another 600 million won from his uncle, Lee Sang-eun, to fund the purchase of the Naegok-dong site.

The counsel said it is discussing details such as the method and the timing of questioning of the first lady with the presidential office Cheong Wa Dae.

The inquiry is highly likely to take place early next week either in written form or a face-to-face interrogation, as the first lady left earlier in the day for the visit to Indonesia and Thailand to accompany her husband.

Meanwhile, three officials from the presidential security service postponed their summons date on Wednesday, the counsel said.

“We plan to summon them once again tomorrow,” assistant special counsel Lee said, adding that their status in the investigation has changed from witness to suspect.

With the change, the number of suspects implicated in the scandal that is looming as a major political issue ahead of December’s presidential election was increased to seven, including Lee Si-hyung and several former high-ranking Cheong Wa Dae officials.

Meanwhile, the team said it is not ruling out raiding Cheong Wa Dae, as it needs to reconfirm some of the data submitted by the presidential office.

Since the allegations were raised by the opposition parties, the presidential office has flatly rejected suspicions the project was an illicit scheme to help the president’s son profit.

Lee later scrapped the project and decided to move into his existing Nonhyeon-dong residence after leaving office next February. (Yonhap News)