President Park Geun-hye’s bodyguard remained quiet on key issues surrounding Park’s relationship to her close confidante Choi Soon-sil and her alleged negligence of duty over the Sewol ferry disaster during the impeachment trial on Thursday, citing national security and a confidentiality clause.

During the fourth hearing of the trial, the Constitutional Court dismissed the stated reasons as unjustifiable, warning that his refusal could be seen as an attempt to conceal something fishy.

Lee Young-sun, the presidential office’s administrative staff in charge of Park’s security, refused to confirm how many times Choi and Park’s other confidants secretly visited her at the presidential office.

Park’s friend of 40 years, Choi is at the centre of a massive corruption scandal which led to Park’s impeachment by the parliament on Dec. 9.

“Whether Choi entered the presidential office is not a national secret. Why should the number of times Choi visited Cheong Wa Dae be kept a secret?” said Kang Il-won, the lead justice of the Constitutional Court.

Read also: Park, Choi deny all charges

“If it is not related to you or your family’s crime, you should testify. The issues surrounding Choi are a crucial point here.”

Lee, suspected of driving Choi in and out of Cheong Wa Dae and closely assisting her, did not confirm whether he saw Choi at the presidential office, saying “I cannot reveal anything related to my job.”

Justice Lee Jeong-mi accused him of committing “perjury” when he denied driving Choi into the presidential office, citing a text message exchanged between him and an arrested ex-presidential aide, Jeong Ho-seong, who is charged with leaking government secrets to Choi.

The ex-presidential aide admitted to having sent the text message, discovered on Jeong’s phone, in which he said that “Choi is coming in.”

The message is suggested to mean that Choi is coming into the presidential office – possibly escorted by Lee.

But Lee admitted that he had first met Choi sometime around the 2012 presidential election, and met her several times at a dressmaker’s shop in southern Seoul while picking up clothes for Park until early 2016.

Allegations have suggested that Lee carried Park’s close friends including Choi and unauthorized doctors in his car to get them into the presidential office without having their identities checked.

Lee also appeared to go back on his earlier statement given during the prosecutorial questioning that he had never delivered money to Choi on behalf of Park.

Choi is suspected of paying for Park’s clothes, which could constitute bribery.

Read also: Court dismisses Park’s explanation on missing 7 hours as ‘insufficient’

Another witness, Ryu Hee-in, former secretary-general of the National Security Council and a member of the parliamentary committee investigating the cause of the Sewol ferry sinking, said that the president was “ultimately” responsible for handling the maritime disaster.

“I cannot understand that the presidential office does not serve as a control tower in cases of disaster, given my past experience (during the Roh Moo-hyun administration),” he said, dismissing Park’s then-security adviser Kim Jang-soo’s claims that the presidential office was not in charge of coping with the accident.

Park’s alleged seven-hour absence and negligence of duty to save people’s lives during the maritime disaster, in which more than 300 people died or went missing, is one of the key elements of her impeachment.

A former CEO and a staff reporter for a local daily also testified on the government’s alleged crackdown on the media outlet since it reported in 2014 on a document revealing Jeong Yun-hoe’s meddling in state affairs and personnel appointments.

Read also: Samsung heir becomes suspect in S Korea political scandal

Jeong is Choi’s ex-husband.

The hearing comes amid growing frustration over delays in court proceedings caused by the continued absence of key witnesses and their reluctance to give detailed testimonies.

Other than the ongoing impeachment trial, Park is facing an investigation by an independent counsel over suspicions that she conspired with Choi and ex-presidential aide An Chong-bum to extort donations and favors from local conglomerates.

Choi’s niece and close associates are all being tried for criminal charges including attempted fraud, abuse of power and coercion.

President Park, Choi, An and Jeong all deny their charges, and even questioning the validity and legitimacy of major pieces of evidence, in what critics see as a tactic to prolong the court proceedings at the Constitutional Court.

But Lee Joong-hwan, Park’s lawyer, said that Park has no intention of delaying court proceedings.

“We are just very busy reviewing more than 40,000 pages of documents,” he said during a briefing Thursday.

Meanwhile, Kwon Seong-dong, chairman of the judiciary committee in the National Assembly, told reporters that the parliamentary committee officially requested Park’s lawyers for explanation on the president’s work from her residence in the presidential office.

Read also: Choi withdraws testimony; An challenges validity of evidence

“The president’s work from home has no legal grounds and it is illegitimate,” he said.

The request comes after the president submitted a document detailing a timeline for what briefings she received and orders she gave on the day of the ferry sinking.

The top court dismissed it as “insufficient,” ordering a resubmission.

A man in Fengshan county, Guangxi Zhuang autonomous region, is being probed for allegedly maltreating his 92-year-old mother by locking her up in a pigpen.

A video has gone viral on Chinese social media showing how the old woman, surnamed Yang, lived in a room measuring less than 10 square meters and containing only a wooden board covered by an old quilt for her to sleep on.

The video, believed to have been recorded by local media, showed that an iron gate outside the room was locked.

The local government sent a team to the house to free Yang.

“She was locked up when we found her, and her son and daughter-in-law were at home at that time,” said Huang Huaming, deputy chief of Jinya town.

The officials contacted Yang’s daughter to take care of her.

The couple said that the man’s mother had asked to live in the room, adding that Yang has suffered from incontinence for years and she asked to move into the room for fear she would contaminate the house her son lives in nearby.

Yang was later transported to the local hospital and after a thorough physical examination she was found to be fragile, but fit.

She has returned home and is now living in her son’s house.

Local police are conducting an investigation and collecting evidence.

“It is true that she has been abused, but the room was not fenced until a couple of days ago, so she wasn’t locked up for years (as the video claimed),” said the local police chief surnamed Wu.

“We doubt whether she lived in the room willingly because we are not sure whether she has a sound state of mind at the age of 92,” Wu added,

Yang’s four children signed an agreement to look after their mother, according to which Yang will continue to stay with her only son, but her daughters will take turns to look after her.

Former UN Secretary-General Ban Ki-moon, upon returning to his home country on Thursday, once again hinted that he would run in the forthcoming presidential election, underlining his past 10 years of experience as the chief official of the international organisation.

He also reiterated his denial over the allegations that he received massive kickbacks from a businessman.

“I have vowed to listen to the people’s opinions once I get back home, and I plan to do so, starting from tomorrow,” the former top diplomat said at a press conference, following his arrival at Incheon International Airport.

“Then with a humble heart, I will make a decision that has nothing to do with my private interests. The decision will not take long.”

Ban, whose two consecutive terms as the UN’s top official ended on Dec. 31, set foot in his home nation on Thursday afternoon, accompanied by his wife Yoo Soon-taek.

As former foreign minister and UN top official, he was cordially greeted by Vice Foreign Minister Lim Sung-nam and Incheon International Airport Corporation CEO Chung Il-young.

Though he yet refrained from directly announcing his much anticipated presidential candidacy, Ban once again expressed the will to become part of the country’s leadership.

“I have long sought to use my insight and experience as UN secretary-general for the sake of my own country,” Ban said, stressing his prestigious career as the chief official of the world’s most powerful international organisation.

When Ban claimed his achievements in promoting world peace, developing impoverished countries, responding to climate change and improving gender equality, loud cheers went up from his supporters’ groups gathered to hear his voice.

“Many have asked me whether I aspire to power,” Ban said, addressing the mounting inquiries on his participation in the presidential race.

“If they mean to ask whether I am seeking to reunite this divided country and to once again make it a first-rate nation, yes, I am ready to give my all.”

He also alluded to his capacity as top diplomat by pointing out the foreign affairs environment of the Korean Peninsula.

“The international situations surrounding our country will deliver a visible impact on our national security, economy and trade,” he said.

“It is urgent to further reinforce the ties with surrounding countries such as the United States, China, Russia and Japan, and to establish relevant countermeasures.”

In an apparent move to distance himself from the current Park Geun-hye administration, which is likely to face a premature termination through Park’s impeachment, Ban expressed regret over the social and political distress his country was in.

“Our nation was torn apart, the economy lost vigour, and society was stained with irregularities,” he said, holding “social leaders” responsible for the current crisis.

“We should put an end to conflicts, vested rights and abuse of power to achieve national unity at all costs.”

His remark was taken as alluding to the extensive corruption scandal centred on Park, an issue which not only triggered record-breaking candlelight protests but also the parliamentary passage of an impeachment bill.

“History will remember the year 2016 and the people who have gathered in the streets under the goal of creating a better country for all. We should never forget the people’s expectations,” he said.

The high-profile figure took a firm stance when denying his alleged involvement in bribery.

“Never during my past 50 years as South Korea’s civil servant and UN official have I done anything against my conscience,” he said.

“It is regretful that some would want to distort or slander my pure intention to contribute to the development of my homeland.”

Ban recently came under fire over a report claiming he had received bribes worth $230,000 from a local businessman.

He immediately filed a petition to the Press Arbitration Commission, but details of the allegations are yet to be clarified.

He also stood up against the criticism that as a freshly retired top official of the international organisation, he should at least take some time before considering his candidacy in the presidential race.

Such concerns are based on a resolution adopted by the UN in 1946, recommending former secretary-generals refrain from taking government posts after retirement.

Read also: Ban returns to S Korea after hinting at presidency run

“I expect the UN to present its official stance on this issue, but to give you my personal view on the matter, I believe that the given clause does not stop me from (assuming) an elected post,” Ban said in answer to reporters’ questions.

After the press conference, the returned top official took the airport railroad for Seoul Station, as part of his gesture to meet with citizens.

On Friday, he is scheduled to pay a visit to the Seoul National Cemetery, located in his resident area Dongjak-gu in southern Seoul, and then to a nearby community centre, according to his spokesperson Lee Do-woon.

Health authorities have confirmed the first case of H7N9 bird flu in a 72-year-old woman native of the Chinese territory of Macau, after she returned from a visit to the southern Chinese area of Zhongshan, the official Xinhua news agency reported.

Three relatives, four ambulance workers, four hospital roommates and 32 healthcare workers have come in contact with the victim, Xinhua reported on Thursday.

They will receive five days of Tamiflu treatment and remain under observation for an additional 10 days, the report said.

In China, over 100 cases of human contamination of H7N9 – a highly pathogenic strain – have been detected, leading to 20 deaths in December, according to the National Health and Family Planning Commission.