Prosecutor General Han Sang-dae will step down on Friday and ask President Lee Myung-bak to "newly appoint" a successor, the official said, adding that he will also offer an apology to the people and announce planned prosecution reform measures on the same day.
Ranking prosecutors of the Supreme Prosecutors' Office (SPO) and a group of senior prosecutors at the Seoul High Prosecutor's Office demanded that Han voluntarily step down to take responsibility as head of one of the most powerful investigative authorities.
The move comes after the prosecutors have apparently realized that bone-cutting efforts are necessary to overcome what they call "the biggest crisis that has ever hit the prosecution."
During a meeting with ranking prosecution officials earlier in the day, Han rejected senior prosecutors' demand for his resignation after urging them to quit instead, expressing strong discontent, according to sources.
The integrity of the prosecution was deeply hurt and the public confidence in the prosecution could not be more dismal, due to recent embarrassing sex and graft scandals involving incumbent prosecutors, and internal conflicts among high-ranking prosecution officials.
A survey released earlier this week showed that the prosecution is seen as the country's most corrupt agency by citizens.
The crisis began when a senior prosecutor came under police investigation on suspicions of receiving bribes from a conglomerate and a notorious swindler.
Kim Kwang-joon was arrested for receiving a total of nearly 900 million won (US$826,000) from Cho Hee-pal, the mastermind of South Korea's biggest pyramid scheme, and the Eugene Group, a mid-sized conglomerate, in exchange for influence peddling.
Following Kim's arrest, Han issued a written apology, saying he felt deeply ashamed and that the organization needed an overhaul.
Just days later, however, it was revealed that a trainee prosecutor had allegedly engaged in inappropriate sexual conduct with a female suspect he was questioning, at his own office.
The 30-year-old junior prosecutor surnamed Jeon is accused of having sexual activity with a 42-year-old female suspect while questioning her about a theft case on Nov. 10. He is also suspected of having sex with the suspect at a motel two days after their first exchange.
Han previously said he will look at all options for a new starting point, to include considering the disbandment of the Central Investigation Unit (CIU) that handles all high-profile cases.
Adding to the crisis, the SPO said Wednesday that it has launched an internal inspection into Choi Jae-kyong, the head of the CIU, on suspicion that he advised Kim Kwang-joon on how to deal with the media while Kim was under investigation by special prosecutors.
It marks the first time that the head of the CIU has come under inspection.
"There were conflicts when exchanging opinions (with Han) regarding the prosecution's countermeasures to recent scandals," Choi said in a statement on Wednesday. "I believe the inspection is the result of that (conflict)."
An inspection team under the SPO on Thursday disclosed the content of a text message between Choi and Kim to the public, saying that the alleged advice has damaged the prosecution's dignity.
Choi advised Kim to avoid "giving the details" during the investigation and to "respond firmly" to reporters, according to the text message released by the team.
Other reform measures being considered include creating an independent investigative body to probe corruption among relatives of the president and senior government officials, officials said.
The prosecution is also mulling over making an independent counsel a permanent fixture instead of on a case-by-case basis, they said.
The prosecution holding the exclusive right to indict, which is always a source of criticism and debate, is also being discussed, they added.
Public pleas for prosecution reform have never been stronger as the two major presidential candidates have laid out their plans to reform the agency, ahead of the December presidential election.