The special investigative team led by independent counsel Park young-soo suspects that another unauthorized figure may have been involved in President Park Geun-hye's medical treatment.
According to sources and local reports, the team has secured text messages exchanged between two of Park's secretaries in May 2013 regarding visits by the "injection lady" to Cheong Wa Dae, allegedly without proper security clearance.
According to the five text messages that have been restored through digital forensics, the person whose identification is unknown and yet to be investigated visited Cheong Wa Dae at night escorted by Park's personal secretary, Lee Young-sun.
The messages were between Lee and Jeong Ho-seong, who is currently standing trial for his involvement in a scandal surrounding Park and her confidante Choi Soon-sil.
This is the latest in a series of suspicions that the president has been regularly seeing doctors not her official doctors with proper clearance for cosmetic purposes or stamina-boosting injection shots, possibly with help from Choi, her friend of 40 years.
Kim Young-jae, a plastic surgeon who has known Choi for years, admitted during a recent parliamentary hearing that he entered Cheong Wa Dae multiple times without security checks to treat Park's skin problems.
It was also revealed by Park's former aide Jeong from earlier investigations that Kim Sang-man had visited Cheong Wa Dae before receiving an official appointment as a presidential medical adviser in August 2013 to give Park placenta injections. Kim has ties to Choi.
On Thursday, the independent counsel summoned South Korean Ambassador to France Mo Chul-min as a witness regarding his possible involvement in the alleged delivery of a "blacklist" of artists to the Culture Ministry from the presidential office.
The 58-year-old former presidential senior secretary for education and culture is suspected to have played a role in delivering the blacklist of some 9,000 artists critical of the government when he was serving as the presidential senior secretary in 2014.
Mo, however, denied his involvement, saying the list was created after he resigned from the post in June 2014.
Former Culture Minister Yoo Jin-ryong is reported to have said that Mo and another former presidential adviser for culture and sports, Kim So-young, handed over the blacklist, which demanded the artists be excluded from receiving cultural funding.
Kim Jae-yeol, an executive of Cheil Worldwide, a Samsung Group company, was also summoned Thursday for allegedly giving subsidies worth 1.6 billion won ($1.3 million) to the Korea Winter Sports Elite Center, which was established by Choi's niece, Jang Si-ho, in June 2015, through meetings with former Vice Culture Minister Kim Jong in August 2015 and earlier this year, a rare case for a new organisation.
Investigators also re-summoned former Presidential Nurse Officer Cho Yeo-ok on suspicions over the "missing seven hours" of Park on April 16, 2014, when a ferry disaster took place.
Park is suspected of undergoing a cosmetic medical procedure during the 2014 sinking of the Sewol ferry, which left over 300 passengers dead or missing.
Cho, whose involvement in the procedure had been rumored, flatly denied most allegations at the hearing last week.
Cho is currently barred from leaving the country.
The independent counsel said it raided offices in Ewha Womans University to secure materials over allegations the school provided preferential treatment to Choi's daughter, Chung Yoo-ra, in the admissions process and grading.
The counsel team said its investigators visited some 10 locations, including related officials' houses and that of former Ewha President Choi Kyung-hee, a month after prosecutors raided 20 locations inside and outside the school, including the president's office and professor laboratories.
The special investigative team also requested an arrest warrant for Moon Hyung-pyo, head of the National Pension Service, on charges of abuse of power in backing the merger between Samsung C&T and Cheil Industries last year.
Moon was detained Wednesday by the independent counsel team on suspicion of having pressured the pension fund to support the Samsung merger deal last year when he was welfare minister.