A special prosecutors' team looking into the scandal surrounding President Park Geun-hye's confidante said Friday it will expand the number of investigators as allegations continue to snowball into different sectors.

The move came after a local court gave a nod to formally arrest Choi Soon-sil, who has maintained close ties to Park for 40 years, over alleged abuse of authority and other irregularities. The 60-year-old has been put under custody since late Monday.

With Choi under detention, the prosecutors' office said they will roll out a thorough investigation on the allegations to reveal the truth and mobilize all available resources. Following the decision to expand the probe, 31 prosecutors will work for the special investigation team, up from the current 22.

The allegations surrounding Choi, who accessed and edited presidential speeches and documents and may have benefited financially from her connection to the chief executive, continued to expand.

Experts said the increase of the investigation team also came amid the rising calls that Park should also cooperate with the probe and respond to questions if the need arises.

Prosecutors, meanwhile, arrested Jeong Ho-seong, a former secretary in charge of the president's private affairs, late Thursday night for allegedly leaking confidential presidential documents that included diplomatic and security issues to Choi. Investigators said they found traces of Jeong's involvement on a tablet PC presumed to have been used by Choi.

Sources said investigators have concluded the abandoned tablet PC initially presumed to have been Choi's does in fact belong to her. The scandal surfaced after a local broadcaster broke the story last month after it retrieved data from the device.

Choi, however, has been claiming the device does not belong to her and that she does not know how to use tablets. Investigators found selfies of Choi along with photos of other relatives, which they say points to ownership.

Lee Kyung-jae, Choi's lawyer, said he accepted the court's decision in regards to the arrest, but made clear this move does not necessarily mean that his client is admitting to the charges leveled against her.

Cha Eun-taek, one of Choi's closest associates in the cultural sector, is also set to undergo questioning after returning home from China next week. (Yonhap)