The independent counsel team investigating the Choi Soon-sil scandal is aggressively taking on every major suspicion tied to President Park Geun-hye and Choi.

The team headed by Park Young-soo has already taken into custody three former senior officials, including an ex-culture minister, on charges of discriminating against “blacklisted” artists and cultural figures. A former Blue House chief of staff and the current culture minister also face questioning.

A prominent writer and professor has been put into custody in relation to the allegations that Ewha Womans University gave illegal favors to Choi’s daughter. Former senior school officials, including the then-president, face the same charges.

While looking into those and other allegations, the team is closing in on the key figures in the influence-peddling and corruption scandal -- Park, Choi and some chaebol tycoons.

In their first major step, the team summoned Samsung heir Lee Jae-yong on Thursday over the allegations that the conglomerate provided Choi with what investigators suspect are kickbacks for government favors.

Lee, who was called in as a “suspect,” was also charged by the National Assembly with perjury over testimonies he made in a parliamentary hearing last month. Prior to Lee’s questioning, which lasted for 22 hours until Friday morning, investigators did not rule out the possibility of seeking an arrest warrant for him.

The central issue in the Samsung case is whether there was a “deal” between Park and Lee over the National Pension Service’s support for a merger of two Samsung subsidiaries in 2015 and the group’s financing of several business projects controlled by Choi and her daughter’s dressage training. Samsung also donated money for a sports consulting company run by Choi’s niece.

Both Park and Lee denied the suspicions. But it is indeed hard to understand why Samsung, which already contributed 20.4 billion won ($17.3 million) to two foundations controlled by Choi, separately signed a 22 billion won contract with a sports consulting firm Choi established in Germany. Much of the money sent by Samsung was used to finance the dressage training of Choi’s daughter.

Investigators suspect that Samsung would not have been so generous toward Choi if it had not asked or anticipated favors, including the pension fund’s endorsement of the merger between Samsung C&T and Cheil Industries. In relation, Moon Hyung-pyo, a former health and welfare minister who also served as the chief of the National Pension Service, has already been taken into custody on charges of pressuring pension fund officials to stand for the merger.

Samsung is not the only conglomerate that faces the ever-widening investigation. Investigators hinted that SK Group Chairman Chey Tae-won would be their next target over allegations that he was granted presidential amnesty in August of 2015 in return for SK’s financial support for Choi.

The Chey case came to the fore again due to a news report about a recorded conversation between Chey, then in prison, and a top SK executive three days before the announcement of Chey’s release on special presidential pardon in August of 2015.

The executive spoke in a kind of code, but his comment insinuated that Park decided to pardon Chey and that she demanded something in return, according to the report. SK donated 11.1 billion won to the Mir and K-Sports foundations, and was approached to contribute more, but the talks broke apart.

All in all, it seems the investigation team is resolute to shed light on any suspicions involving Park, Choi and tycoons. The most crucial part of their efforts will be personally questioning Park, who state prosecutors had concluded conspired with Choi and senior officials in extorting money from conglomerates and offering favors in return.

The Choi scandal is a painful reminder that the long tradition of the government in power twisting the arms of conglomerates to donate money to the president’s pet projects and reward them with favors.

It is true that businesses are the weak side in this collusive relationship, but as in the case of conglomerates implicated in the Choi scandal, they too exploit it to pursue their own interests. Which means this bad tradition cannot be cut without self-reflection and determination on both sides.