The fate of a Chinese researcher believed to be the world's first Covid-19 patient remains a mystery despite a year-long search by Western intelligence officials investigating the origins of the pandemic.
Huang Yanling, who worked at the Wuhan Institute of Virology, was one of scores of doctors, scientists, activists and journalists who disappeared during the Chinese Communist Party's suspected cover-up.
During the early weeks of the outbreak last February, rumours swirled on Chinese social media that the graduate student was "patient zero", creating a direct link between the controversial lab and the virus outbreak.
Chinese officials quickly stepped in to censor the reports from the internet.
The Wuhan Institute of Virology denied she was patient zero and insisted, without evidence, that she was alive and well elsewhere in the country – while scrubbing her biography and image from its website.
A post purporting to be from Huang later appeared on social media platform WeChat.
"To my teachers and fellow students, how long no speak," the message said. "I am Huang Yanling, still alive. If you receive any email (regarding the Covid-19 rumour), please say it's not true."
Her former boss made a separate post on social media claiming that she had left the institute in 2015, while a Chinese news agency claimed that it had spoken with her new employer but provided no other details.
A grainy photo of the young woman in her 20s with long hair seen peering out from behind a colleague – salvaged from the website and circulated online – is the only known photo of Huang.
According to the UK's Mail on Sunday, which has also attempted unsuccessfully to track her down, little else is known about her other than that her name is included among the authors of three scientific papers issued by the institute between 2013 and 2015.
The Mail on Sunday says Western governments and intelligence agencies have tried and failed to track down Huang, sparking fears she is either dead or being detained by Chinese authorities.
Huang's disappearance had earlier been cited in a 15-page dossier prepared by Western governments – published by The Sunday Telegraph in May last year – laying out evidence the virus had escaped from the lab.
The Mail on Sunday says its own extensive inquiries within China, including messages to her former colleagues, have also turned up empty.
Despite China's internet censors stamping out discussion of Huang, many social media users continue to speculate about her fate, with some claiming she may have been hastily cremated.
"Everyone on the Chinese internet is searching for Huang," one blogger wrote, according to the Mail on Sunday. "Most believe she is dead."
Secretary of State Mike Pompeo told the Mail on Sunday in a statement that the Chinese Communist Party had prevented investigators from interviewing researchers from the Wuhan Institute of Virology "including those who were ill in the fall (autumn) of 2019".
"Beijing continues today to withhold vital information that scientists need to protect the world from this deadly virus and the next one," Pompeo said.
It comes as US officials step up their attacks on China over the pandemic, claiming they have explosive new evidence that proves Covid-19 leaked from the lab.
Pompeo earlier demanded the World Health Organisation launch an investigation into the possibility the virus was result of an "accidental" lab leak.
He said US intelligence agencies had found scientists at the Wuhan Institute of Virology fell ill in the autumn of 2019 with symptoms consistent with Covid-19, earlier than previously believed.
"This raises questions about the credibility of WIV senior researcher Shi Zhengli's public claim that there was 'zero infection' among WIV's staff and students of SARS-CoV-2 or SARS-related viruses," Pompeo said.
The first cluster of cases was discovered in December 2019 in Wuhan, with early reports linking the outbreak to a controversial "wet market" that sold and butchered exotic animals in disgusting conditions.
The "patient zero" of the Huanan market had previously been named as a 57-year-old seafood merchant, a woman named Wei Guixian, who first started to feel sick on December 10.
On Thursday, the WHO's team of experts arrived in Wuhan to begin their investigation into the origins of the virus, which has now killed more than two million people globally.
"We need to be very careful about the use of the phrase 'patient zero' which many people indicate as the first initial case," Maria Van Kerkhove, the WHO's Covid-19 technical lead, told a press conference.
"We may never find who the patient zero was."
Western governments believe that the body has largely ceded control of the investigation to China, leading to fears of a whitewash.
"Unfortunately, this has become a political investigation," Singapore-based Australian virologist Wang Linfa told The New York Times in November. "Whatever they do is symbolic."