Prosecutors probing the Sung Woan-jong scandal are set to indict South Gyeongsang Gov. Hong Joon-pyo and former Prime Minister Lee Wan-koo soon on charges of receiving illicit money from the late construction tycoon.

The indictment of Hong and Lee concludes the first phase of the investigation into allegations that Sung offered illegal money to influential politicians. Hong and Lee became the first targets after Sung, before ending his own life, left a memo and recorded interview detailing how and when he delivered money to both of them.

Now the focus of the probe should turn to the six other politicians to whom Sung alleged or hinted he gave illicit money. This means the probe is now heading toward the 2012 election funds of both President Park Geun-hye and Moon Jae-in, who now leads the main opposition party.

In the memo and the interview, Sung alleged that he gave money to key managers of Park’s campaign team, including Rep. Hong Moon-jong, Incheon Mayor Yoo Jeong-bok and Busan Mayor Suh Byung-soo.

As the prosecution continued to dig into the allegations, more circumstantial evidence surfaced. A former executive of Sung’s construction firm Keangnam Enterprises testified that he delivered 200 million won ($183,000) of Sung’s money to a senior member of Park’s campaign team before the 2012 presidential poll.

Another associate of Sung said that he helped the tycoon put 600 million won into three bags, which he claimed were delivered to two ruling party lawmakers and one opposition politician.

These testimonies back Sung’s remarks that he provided illegal political funds to both the ruling and opposition camps. He once remarked that it did not matter who wins the election because he contributed money to both sides.

Even without this circumstantial evidence, it is not hard to imagine that Sung, who maintained wide connections, spent his ill-gotten money ― he allegedly embezzled huge sums of company funds ― indiscriminately on politicians and senior government officials.

It is no secret that candidates ― ruling or opposition ― collected and spent money in excess of the legal limits during the past election campaigns. The Sung scandal once again confirmed this reality.

Prosecutors ought to conduct a thorough probe into Sung’s contributions to the Park and Moon campaigns and the overall campaign finances of the 2012 presidential elections.

As Park stressed several times, there should be no sanctuary in the probe into the Sung scandal. It is needless to say the “no-sanctuary” principle should be applied to both Moon and Park herself.