The essence of the Daejang-dong scandal lies in breach of trust, and Yoo Dong-gyu is a suspect at the center of the scandal.

When he was an acting chief executive of Seongnam Development Corp., a public enterprise affiliated with Seongnam City, Gyeonggi Province, he pushed a land development project in Daejang-dong, Seongnam, in a way that allowed several individuals to take astronomical profits, incurring an enormous loss to the corporation and the city.

However, in taking his case to the court Thursday, the prosecution did not include a breach-of-trust charge in the indictment against him.

It did not hold him responsible for the crime of causing a huge loss to the corporation as a result of not inserting an excess earning redemption clause in a business agreement with private-sector shareholders.

When it requested an arrest warrant for Yoo, the prosecution included both bribery and breach-of-trust charges. It is rare for the prosecution to drop a charge from an arrest warrant when it indicts a suspect. The court ruled the charges as well-grounded and the prosecution arrested Yoo.

Like the court, few people would believe that Yoo is clear from the charge of causing losses to Seongnam. It is questionable if the prosecution has a will to investigate the scandal thoroughly. It is just beating around the bush.

The success of investigation depends on finding out who really played a leading role in pushing the project in such an irregular way. Naturally, Lee Jae-myung, then Seongnam mayor, should be subject to investigation because he gave ultimate approval on important matters such as the profit distribution scheme of the project.

If the prosecution had indicted Yoon on the breach-of-trust charge, Lee is likely to be implicated in controversies over whether he should face the same charge.

As to its dropping of the charge, the prosecution says that it will keep investigating, but it looks unlikely that it will add the charge later. It has already secured witness testimonies that indicate that the charge should be applied. There is no news yet that it is tracking suspicious movements of funds. We are left to wonder if it dropped the charge out of consideration that Lee was chosen as the ruling party’s presidential candidate.

For an effective investigation, the timing is very important, but the prosecution has dawdled.

It belatedly raided the Seongnam City Hall on Oct. 15 but left the mayor’s office untouched. Finally, it searched the mayor’s office on Oct. 21, but this did not happen until its fifth raid on the municipal building, more than 20 days after it started its investigations. It is unclear if it secured meaningful information.

A new allegation surfaced that Yoo talked with someone close to Lee by telephone for two hours before he threw away his mobile phone when the prosecution raided his residence.

In a parliamentary audit of the Gyeonggi provincial government, Gyeonggi Gov. Lee said he was told that Yoo had attempted suicide shortly before the search began.

It is hard to believe he was lying, considering perjury in a parliamentary inspection is punishable. There were no news reports at all about Yoo’s suicide attempt. His apparent slip of tongue hints at close ties with Yoo. Lee equivocated, saying he could not remember who told him the story.

The prosecution did not make proper efforts to find out whether there was someone who pulled the strings behind Yoo over the project in question. And yet it dropped the breach-of-trust charge from Yoo’s indictment, effectively giving up on probing Lee, even though related documents contain the mayor’s signature.

It is no small number of things that point to negligence by the prosecution. It rushed to request a warrant for another suspect who allegedly bribed Yoo only to see the court reject the ill-prepared writ. The police found the mobile phone that Yoo had thrown out the window by checking nearby surveillance camera footage that the prosecution did not. Prosecutors released Nam Wook, who is said to have contributed substantially to the design of the project.

The prosecution is bringing disgrace on itself.