The investigation into the Seongnam land development scandal has resumed following setbacks after some members of the team tested positive for COVID-19.

Investigators at the Seoul Central District Prosecutors Office on Monday called in asset management firm Hwacheon Daeyu's largest shareholder Kim Man-bae and lawyer Nam Wook for questioning.

The two were arrested last week but their summons had to be delayed after six members of the investigation team, including the lead prosecutor, were infected COVID-19.

The entire team has since been tested and those with negative results returned to work Monday.

Prosecutors are expected to pick up speed as the trial of Yoo Dong-kyu, the former acting president of Seongnam Development Corporation, starts Wednesday. Also, arrested suspects, including Kim, will be released if indictments are not filed within 20 days.

Kim and Nam are accused of colluding with Yoo and others so that Hwacheon Daeyu would reap enormous gains from the project while Seongnam Development Corporation incurred losses.