Former President Lee Myung-bak is due to appear at the Seoul Central District Prosecutor’s Office at 9:30 a.m. Wednesday for interrogation as a suspect in a string of corruption allegations which include bribery, abuse of power, embezzlement and dereliction of duty.

Lee, who was in office from 2009 to 2013, faces nearly 20 criminal charges including receiving illicit funds of some 11 billion won ($10.3 million) from the state spy agency, individuals and corporates, including Samsung. The prosecution subpoenaed the ex-president after investigating corruption allegations involving numerous high-ranking figures, including his former presidential aides and his family members over the past five months.

Three lawyers have registered to attend the interrogation to defend Lee. They are Kang Hoon, 64, a judge-turned-lawyer who also served as Lee’s former presidential legal assistant, Pi Young-hyun, 48, and Kim Byung-cheol, 43.

Lee stayed at home on Tuesday with his lawyers for a last-minute check, as fierce legal arguments are expected during the interrogation, according to Kim Hyo-jae, Lee’s former presidential senior secretary for political affairs.

The prosecution has reportedly been preparing some 100-page draft questionnaires for the interrogation of the former state chief.

“It is essential to investigate Lee in order to uncover the truth in a transparent and efficient way,” a prosecution official said, when it subpoenaed Lee last Tuesday. “We’re not considering calling him in for questioning multiple times.”

While it is a typical practice to end a prosecutorial probe as late as before midnight, some expect the interrogation session to continue to the next day as Lee apparently has prepared to defend himself.

Lee has insisted that the prosecution’s investigation is “political revenge” by the liberal Moon Jae-in administration, and has denied all charges against him. As for Wednesday’s interrogation, he is also expected to maintain his innocence.

Over the controversial auto parts maker DAS -- which belongs to Lee’s eldest brother Lee Sang-eun on paper -- the prosecution has concluded that former President Lee is the real owner after obtaining testimonies from related figures including his nephew Lee Dong-hyung, Lee Sang-eun’s son. The prosecution holds Lee accountable for many irregularities surrounding the auto parts manufacturer, including the creation of a slush fund totaling some 30 billion won.

The ex-president, however, denies the allegation and insists that the prosecution does not have any solid evidence, and that he does not own any share of the company.

As for the $5 million litigation fee that Samsung Electronics allegedly paid to law firm Akin Gump between 2007 and 2009 on behalf of DAS, the prosecution sees it as a kickback to the former president. Lee is likely to fight back, saying he was not aware of the involvement of Samsung in the first place.

While several former Cheong Wa Dae officials are suspected of having received illicit funds from the National Intelligence Service during the Lee administration, the prosecution has identified Lee as the “main culprit” and holds him accountable for the bribery totaling 1.75 billion won.

Lee is expected to maintain that he has no knowledge of the illicit funds involving the nation’s spy agency, but prosecutors said it may be difficult for him to prove his innocence, as his close aides have testified that they received the money under Lee’s instructions.

As for other suspicions over bribery in return for favors, Lee is also expected to deny his involvement, as he says he was not aware of such money transfers to him or his associates.

He is suspected of having received some 2.25 billion won from Lee Pal-sung between 2007 and 2011 in return for his appointment as chairman of Woori Finance Holdings, and also accepting 500 million won from Daebo Group and 400 million won from a former lawmaker in exchange for business and election favors.

Under the Act on Aggravated Punishment of Specific Crimes, receiving bribes of 100 million won or more is subject to at least 10 years in jail. The maximum penalty is life imprisonment.

By Jo He-rim (herim@heraldcorp.com)