It is illegal for a person to put his money in an account opened in the name of another person. But an older brother of President Lee Myung-bak’s did so in violation of the law on the use of real names in financial transactions.

Over the past two years, Rep. Lee Sang-deuk of the ruling Grand National Party deposited as much as 800 million won in an account held by a female secretary of his. The money was found when prosecutors were looking into an allegation that one of his aides took as much as 1 billion won in bribes from a businessman.

The lawmaker also breached the law on the ethics of public officeholders because, as he acknowledged, he did not include the money in a report on the assets in his possession that he was statutorily required to file each year. He offered no convincing explanation as to why he had to hide the money in violation of the law.

A key question in this case is from what source the money came, given that funds of dubious origin are often parked in borrowed-name accounts. But the lawmaker did not specify the origin of his money in a report he submitted to the prosecutors’ office.

Adding to suspicions is a news report that the lawmaker’s assistant used the account for the laundering of the 1 billion won he had taken in bribes. Prosecutors are inquiring where the money has gone.

The prosecution is also looking into another corruption case, which directly involves the lawmaker this time. They reportedly obtained a statement that Kim Han-in, the board chairman of a broadcasting college, was suspected of giving the lawmaker 200 million won in 2007 in the hopes of winning the nomination for a parliamentary election. A report said they were told by an accountant of the college that Kim put 2 million won in cash into two boxes and probably sent them to the lawmaker. But the prosecutors said Kim refused to say how he spent the money.

Given the lawmaker’s relation to the president, the prosecutors appear to have been exercising great caution in their investigation into each case involving the lawmaker. But it is high time to set it in full swing. One of the first steps they will have to take in this regard is to summon him for an inquiry as soon as possible. A demand for written clarification will not suffice.