The fact that he almost never appeared online surfaced after his plane touched down at John F. Kennedy Airport in New York on Monday night, international media reported.
The man known as Zhen Cheng Li has little contact with anyone in the city and, separately, was a reluctant Internet user, if he went online at all.
Following a 2012 FBI inquiry, he was eventually detained and charged with unlawful retention of national defense information, according to the US Attorney’s Office for the Eastern District of Virginia.
There are suspicions that Lee might have played a key role in Beijing’s disruption of the American spy network in China, NBC news reported citing sources close to the case.
"Apparently, he operated here in Hong Kong very discreetly and not many people knew him," said former police superintendent Clement Lai Ka-chi, who had a brief encounter with Jerry Chun Shing Lee in the past.
"I am not surprised," was his comment on suspicions that Lee might have leaked sensitive information to Beijing, South China Morning Post reported.
The New York Times wrote that China was considered the US intelligence’s biggest vulnerability, with Beijing having liquidated – killed or imprisoned — as many as 18 to 20 operatives over the past seven years.
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Lee, a naturalized American citizen currently living in Hong Kong, became engaged in spy work with the CIA in 1994. He was then "trained in methods of covert communications, surveillance detection, recruitment of assets, operational security" and "documenting, handling and securing classified material."