Prosecutors have indicted three key figures in their investigation into alleged lobbying and favoritism tied to the Seongnam land development project.

The Seoul Central District Prosecutors' Office on Monday indicted Kim Man-bae, the biggest shareholder of asset management firm Hwacheon Daeyu, as well as Nam Wook and Chung Young-hak, owners of its affiliates.

Kim and Nam face charges of dereliction of duty and bribery under the additional punishment law on specific economic crimes. Chung, who provided prosecutors with an audio recording transcript, was indicted without pretrial detention as an accomplice.

They are accused of colluding with Yoo Dong-kyu and Chung Min-yong, two former executives at Seongnam Development Corporation, to secure a hefty profit for the asset firm while inflicting losses for the public company.

The scheme allowed the asset firm and its seven affiliates to rake in about 183 billion won in profits.

Kim and Nam are also suspected of providing Yoo and Chung with company funds worth 500 million won and three-point-five billion won, respectively, in bribes.

The indictments, however, did not mention involvement by then-Seongnam City Mayor Lee Jae-myung, who is the ruling Democratic Party's(DP) presidential candidate.