As early as next week, former President Lee Myung-bak will be added to the already shamefully long list of former leaders who have been summoned for questioning over allegations of wrongdoings they committed, most them while in office.

Lee, who occupied Cheong Wa Dae from 2009-2013, faces an assortment of charges, including bribery and abuse of power. The prosecution which has been digging into Lee and people close to him for months believe -- among other things -- Lee and his associates took illegal money amounting to more than 10 billion won ($9.3 million).

The money includes 1.7 billion won Lee’s top aides received from the audit-free “special activity account” of the National Intelligence Service. Ousted former President Park Geun-hye also faces a similar charge.

Lee is also suspected to have embezzled company fund of DAS, an auto parts firm which prosecutors believe is owned by Lee. One of Lee’s brothers holds the largest stake of the company, and Lee has been denying since before the 2008 presidential election that he was the real owner.

Prosecutors said their investigation led to the discovery of slush funds amounting to 30 billion won and suspected tax evasion involving the company. The DAS investigation primarily targeted Lee’s brother, Lee Sang-eun, and son Si-hyung, who is an executive of the company.

Prosecutors said they also found that Lee’s aides had Samsung Electronics pay 6 billion won in litigation fees for DAS, which was engaged in a legal battle in the US to retrieve investment.

All these and other charges surfaced during the prosecution’s massive probe into people close to Lee, including his family members, relatives and former aides. Some are already in custody and prosecutors say they were confident of indicting Lee because he was behind many of the misdeeds and illegal activities.

The prosecutors’ confidence was strengthened by a series of new cases in which Lee is suspected of having used his position to fatten his personal health.

Lee is suspected of having received -- through his eldest brother and former National Assembly Vice Speaker Lee Sang-deuk and his son-in-law -- 2.2 billion won from Lee Pal-sung, former chairman of Woori Financial Group, in return for appointment favors.

The list of dirty money deals goes on: Lee is suspected of taking 400 million from Kim So-nam, a former lawmaker, in return for the ruling party’s nomination for parliamentary election. Lee is also suspected of receiving bribes from Daebo Group, which runs expressway rest stops, and other businesses in return for government contracts and other favors.

All those charges should be judged by the court in the end, but testimonies and evidence secured by the prosecution so far point to the high possibility of wrongdoings on the part of Lee. Most disgusting is that the chief executive did not have qualms about taking advantage of his position and power to pocket personal money.

So it is hardly strange that public antipathy toward Lee is growing, which weakens his argument that the ongoing investigation is political retaliation being perpetrated by the government of President Moon Jae-in. A latest public opinion survey found that 67.5 percent of Korean favor putting Lee into jail.

But what the prosecution should not forget is that there are some grounds to the argument that an investigation into Lee has something to do with the Moon administration’s grudges against the former leader. This calls on prosecutors to base their actions purely on the law.

On his part, Lee, as a man who occupied the nation’s highest elected office for five years, has a minimum obligation to offer sincere apologies, tell the truth and take responsibility for whatever wrongs he committed.

The Lee cases should be another reminder that many things ought to be done to keep presidents from being dragged into the vicious cycle of committing misdeeds in office and facing punishment after retirement. 

Most urgent is institutional reform, like curbing the power of what is called “imperial presidency” through amendment of the Constitution.