Jeff Gillis has gone public with the six-month detention and subsequent arrest of his wife, Sandy Phan-Gillis, while on a business trip in China, on the cusp of President Xi Jinping’s visit to Washington, D.C.

Phan-Gillis, a U.S. citizen and businesswoman based in Houston, was stopped before getting aboard a flight home on a business trip to China. Her friends and family have not seen her since. Phan-Gillis had not been formally arrested until the weekend of September 19, her husband tells the Houston Chronicle, noting that she was arrested while on a trip promoting commerce between major Chinese cities and Houston, alongside Houston pro-tem Mayor Ed Gonzalez and several other city officials.

“Sandy was nowhere to be found, but it was daytime, it was busy, and there was nothing out of the ordinary, so we thought maybe she had gone to the restroom,” Gonzalez said of her disappearance at an airport on the border between Guangdong and Macau in March. She later told businessman Vincent Chau to tell the group to move ahead to the United States, as she would stay behind to handle a “personal matter.”

“I thought, ‘Man, that’s bizarre, she should have let us know,'” Gonzalez told the Chronicle.

According to SaveSandy.org, a website set up by her family to bring her home, Phan-Willis spent six months “under residential surveillance by State Security in Nanning, Guangxi,” but has since been moved to a “formal detention facility,” though she has not been charged with a crime. “Sandy is being investigated for spying and stealing state secrets. However, to date there has been no detailed explanation for her detention,” the site explains.

Her family and friends describe Phan-Willis as “in very poor health (with high blood pressure, high cholesterol, and high blood sugar)” and fear for her safety under arrest. They do note that she dos not appear to have been tortured while detained, according to American officials handling the situation.

She has allegedly been held since under house arrest, but not charged with any crime. Last weekend, she was arrested. Chinese Ministry of Foreign Affairs spokesman Hong Lei told reporters Tuesday that she was, in fact, arrested “on suspicion of activities harmful to Chinese national security.”

“We hope that the outside world will respect China’s handling of this case according to law,” Hong added. American officials have yet to comment on the case.

“It is the most stupid politics in the world to arrest a U.S. citizen the week that Xi Jinping is coming to the United States for a state visit on political charges of spying,” Jeff Gillis told The New York Times, adding that he did not “want to be disruptive” of Xi’s diplomatic visit, but “I just want to get my wife back.” Gillis told the Houston Chronicle he, indeed, timed his announcement to coincide with Xi’s visit, in the hopes that it would be more widely publicized and have a better chance of prompting the Chinese government to act on her behalf.

“She has done so much for U.S. China relations, it astounds me to think that China would act this way to a really good friend,” Gillis said of his wife.

Phan-Gillis is ethnically Chinese, born in Vietnam, and arrived as an exile in the United States as a teen. She is the latest in a string of such arrests, with the most recent being the eight-year conviction of American geologist Xue Feng for allegedly committing “industrial espionage.” Feng lost his appeal.

Phan-Gillis’s arrest is particularly bad publicity for China at a time in which its state media is struggling to paint its leaders as benevolent and peaceful despite abundant evidence to the contrary. On Xi’s visit to the United States, state news outlet Xinhua has quoted the head of state as claiming that the U.S.-China relationship “transcends time and space” and praised him for his “epic bid for better U.S. ties.” Xi has also stated, contrary to all Chinese military activity in the South China Sea, that China is “not going after some kind of military adventure–it never crosses our mind.”

The United States has arrested Chinese nationals on similar espionage charges, as well. In May, American officials arrested six Chinese suspects–three of them professors–for allegedly attempting to steal trade secrets to build more efficient mobile phone technology. Xinhua dismissed these arrests as a product of “Washington’s growing paranoia” against China.