Prosecutor General Lee One-seok has expressed his condolences over the death of the former chief of staff of main opposition Democratic Party(DP) leader Lee Jae-myung.

In a meeting of the department heads of the Supreme Prosecutors' Office on Monday, he said there was nothing more precious than a person's life and delivered his condolences to the deceased, surnamed Jeon, and his bereaved family.

He also urged the prosecution to take caution when practicing the law to prevent the recurrence of such an incident in the future.

The former chief of staff was found dead in an apparent suicide on Thursday.

Jeon, who served as Lee's chief secretary while he was the mayor of Seongnam city, was questioned by prosecutors over allegations that Lee engaged in bribery in the form of corporate donations to the city's football club during his term as mayor.