The only son of South Korean President Lee Myung-bak is under investigation for tax evasion over a land deal on his father’s retirement home.

Prosecutors said Lee Si-Hyung was not among the three people indicted but that they would take his tax records to the National Tax Service for review.

The younger Lee allegedly received 600 million won ($542,000) from the president’s brother, Lee Sang-Eun, to purchase the land. The former leader was to stay at the home after leaving office in February but investigators are looking at whether or not the younger Lee paid necessary tax, AFP reports.

Three people from the presidential security service were indicted on breach-of-trust charges, including the former head, following a month-long probe into alleged irregularities in the deal.

The land was jointly purchased by the president’s son and the presidential security service. But prosecutors claimed the sum was not split evenly, with the presidential service covering more, using public funds, while Lee’s son paid the remainder.

President Lee has scrapped his initial plans and will retire to an existing private property in Seoul. The Presidential Blue House on Wednesday expressed “regret” at the prosecutor’s findings.